Paper, Memory or Glass? How Pilots Really Use Checklists, from the Cessna 172 to the Boeing 787

On 31 May 2014, a Gulfstream IV accelerated down runway 11 at Bedford, Massachusetts, and never left the ground. The gust lock, a mechanical pin that clamps the flight controls while the jet is parked, was still engaged. The jet overran the runway, crossed a ravine and burned. All seven people on board died.

The two pilots were experienced, and their checklist had an item that would have caught the lock. When the NTSB pulled the jet's flight data, it found something worse than one bad day: before 98% of their previous 175 takeoffs, this crew had not done a complete flight control check. They hadn't forgotten their checklist once. They had stopped doing it years earlier.

Seventy-nine years before Bedford, another airplane took off with its controls locked. That crash is the reason checklists exist at all. This article is about everything in between: how pilots actually use checklists today, from a student's laminated card in a 1976 Cessna 172M to the self-ticking electronic checklist of a Boeing 787. We'll cover read-do vs do-verify, the shortened cards flight schools hand out vs the POH, what belongs in memory and what never should, what airline captains on the Boeing 737, Airbus A320, Embraer E-Jets and ATR 72-600 really look at, what the FAA and EASA actually require, and what to do when the radio and the transponder die together. It's all backed by accident reports, NASA research and the rules themselves.

Key takeaways

• Checklists were born from a crash. The Boeing Model 299, prototype of the B-17, crashed at Wright Field on 30 October 1935 with its elevator locked. Checklists followed, and 12,730 B-17s were built after it.
• There are three ways to run one. Do-verify (do the flow from memory, then confirm with the list) for normal procedures; read-do (read a line, do it) for abnormal and emergency procedures; and challenge-response, where one pilot reads and the other answers. The FAA has said it won't accept do-verify for non-normal procedures without substantial evidence.
• Checklists fail quietly. NASA observers counted an average of 3.2 checklist deviations per airline flight, and crews caught only 14% of them. "Responding without looking" was one of the two most common slips.
• Memory items should be few. FAA guidance says avoid them, and if you must have them, use fewer than three, with no conditional steps. The UK CAA says ideally under four and never more than six.
• Shortened checklist cards are legal but subordinate. In the US no FAA approval is needed to customize a Part 91 checklist, but the AFM/POH always takes precedence. EASA's guidance for private pilots says to use the manufacturer's latest checklists.
• Europe makes it the law. Under EASA's Part-NCO, the pilot in command of even a private Cessna is legally responsible for "ensuring that all operational procedures and checklists are complied with." No equivalent rule binds a US private pilot in a light single, though every FAA checkride tests checklist use.
• Airliners are split. Boeing's 777, 787 and 747-8 run electronic checklists that sense switch positions. The 737 still flies with paper. Airbus uses ECAM for failures, with fully electronic normal checklists on the A220, A350 and A380. Embraer and ATR mix EICAS alerts, paper and tablets.
• Squawk 7600 assumes a transponder with power. An electrical failure can kill the radio and the transponder together. Then the lost-comms checklist has nothing left to squawk, and a phone call to ATC may be the only way to talk to anyone.
• Glass is coming to light aircraft. Cirrus's 2024 G7 SR-series links checklists to its crew alerting system, and Garmin's G1000 NXi loads custom checklists from an SD card. Most of the world's trainers still fly with paper.

The 1935 crash that invented the checklist

In 1935 the US Army Air Corps held a fly-off for a new long-range bomber. Boeing's entry, the four-engine Model 299, was the clear favourite: faster, bigger and longer-legged than anything else in the competition.

On 30 October 1935, at Wright Field in Dayton, Ohio, Major Ployer P. Hill lined it up for an evaluation flight with Boeing's chief test pilot Leslie Tower on board. The bomber climbed to about 200 feet, pitched up, stalled and crashed. Hill and Tower died of their injuries. The board found the direct cause was that the elevator control had been left locked.

The Model 299 was simply more airplane than one person could reliably remember. It had four engines with mixture and propeller controls, cowl flaps, retractable gear, flaps, trim tabs and control locks. Douglas won the production contract. But the Air Corps still bought 13 test aircraft from Boeing, and it did something new: it wrote down the steps the crew had to verify before takeoff, before landing and at engine start, and made crews read them.

The Model 299 became the B-17 Flying Fortress, and 12,730 more were built. You may have read that B-17 crews then flew 1.8 million miles without an accident. The story is popular and appealing, but we couldn't find a primary record behind it, so treat it as legend.

The idea spread far beyond aviation. In 2009 the World Health Organization's surgical safety checklist, explicitly modelled on cockpit practice, was tested in eight hospitals. Deaths fell from 1.5% to 0.8%, and inpatient complications from 11% to 7%. Surgeon Atul Gawande's book The Checklist Manifesto popularised the lessons he took from Boeing's checklist designers.

Read-do, do-verify, challenge-response: the three ways to run a checklist

Most pilots learn "use the checklist" as if there were one way to do it. There are at least three, and mixing them up is one of the most common errors airline observers record.

The FAA's Airplane Flying Handbook puts it plainly for light aircraft: a checklist is "a memory aid," and checklists "need not be 'do lists'": a pilot can act first, then verify, with the emphasis on the check in checklist.

Airline practice is stricter. An FAA human factors study published in January 1995 noted that operators have traditionally preferred do-verify for normal checklists. It also said the FAA would not approve or accept do-verify for non-normal procedures without substantial evidence. Airbus's own standard operating procedures put it bluntly: normal checklists are not read-and-do lists. The pilot flying completes the flow, then calls for the checklist, and the pilot monitoring reads it.

Here's what that looks like in a light airplane. On the left, a short normal checklist that a student should do from a flow and then confirm. On the right, an emergency checklist to read and do, with its one memory item highlighted:

Boeing's checklist designer Daniel Boorman, whose advice Gawande quotes at length, adds a few rules of thumb: a good checklist is short, covering only the critical steps an expert might miss. It is not a how-to manual. It has a clear pause point where it should be run, and usually somewhere between five and nine items. NASA researchers Asaf Degani and Earl Wiener went further in their landmark 1990 study of airline checklists, Human Factors of Flight-Deck Checklists. They found one airline checklist with 76 items for a single task and called that "somewhat absurd."

Checklist hygiene: the slips that kill

Here's the uncomfortable truth: having a checklist doesn't protect you. Running it properly does, and pilots, including very good ones, are bad at that.

In 2010, NASA researchers Key Dismukes and Ben Berman published the results of watching 60 ordinary airline flights from the jumpseat at three carriers. They logged 899 deviations from procedure. 194 involved checklists: an average of 3.2 checklist slips per flight. Only 14% of the checklist deviations were caught and corrected. The two most common types made up nearly half of the total:

1. Flow-check performed as read-do (48 cases): the crew skipped the flow and just read the list, losing the double check the method is designed for. 2. Responding without looking (43 cases): answering a challenge from habit. In one example a captain answered "On" to "APU bleed" while the bleed was off.

The others were items omitted or done incompletely, poor timing, checklists done from memory, and checklists never started at all.

The accident record shows what those slips cost. Look how often the killer is a single word, said without looking:

In general aviation the pattern repeats on a smaller scale. An NTSB safety alert counted more than 50 fuel management accidents a year from 2011 to 2015. 95% of them were blamed on the pilot rather than the fuel system. In one example, a Beech 19A's fuel selector had been left OFF after an annual inspection, and the pilot "did not use a checklist." AOPA calls gear-up landings and gear collapses general aviation's most costly problem, at about $70,000 per incident.

Ten rules of checklist hygiene

These are distilled from FAA Advisory Circular 120-71B, ICAO's design guidance (Doc 8168 Volume III), EASA's guidance for private pilots, the UK CAA's CAP 676 and the NASA research above:

• Look, touch, then speak. Find the switch, put a finger on it, and only then answer. The FAA's Pilot's Handbook of Aeronautical Knowledge notes that many solo pilots read the checklist out loud and touch critical controls.
• Answer with the actual state, not "checked." "Flaps: ten, ten, green" beats "Flaps: set." ICAO's design guidance tells operators to avoid responses like "set," "checked" or "completed."
• Use the method the list was designed for. Flow first, then verify, for normal lists. Read and do, line by line, for abnormals.
• If you're interrupted, go back. The FAA's advice is "If interrupted, restart from the beginning." EASA's guidance for private pilots says to restart interrupted pre-takeoff checks "from a safe point prior to the interruption."
• Run it at the right place. Finish taxi and before-takeoff items well before the runway. ICAO says not to do the takeoff checklist on the active runway.
• Keep the flight deck sterile. Delta 1141's long off-duty conversation during taxi was cited in the NTSB's findings.
• Close the loop out loud. End with "Before takeoff checklist complete" so the next one isn't started on top of a half-done one.
• Never let "I always do it" replace the list. Habit is exactly what the Bedford crew had.
• Use the checklist for the airplane in front of you. Not the one you trained in, and not one from a different model year (more on that below).
• One checklist at a time. If you have to stop, mark your place, or use a tool that marks it for you.

POH checklists vs the card in your flight bag

Every light airplane's Pilot's Operating Handbook follows the same basic layout, set by the General Aviation Manufacturers Association's Specification No. 1. Section 3 has the emergency procedures and Section 4 the normal procedures. Each starts with a checklist and then gives "amplified procedures": the same steps with explanations, cautions and the reasons behind them.

Almost nobody flies with the POH open on their lap. Pilots fly with a checklist card: a laminated sheet, a spiral flip book, or a list on a tablet. Very often it isn't the manufacturer's at all. It's a version the flight school or club wrote: shorter, reordered and adapted to local procedures.

Here's a real one: the before-takeoff list from an Israeli flight school's Cessna 172P checklist booklet, which ZuluCheck transcribed. Compare it with the 1982 Cessna 172P POH: the school added three lines the POH doesn't have, highlighted below. It also moved the seat belt and fuel quantity checks elsewhere and changed strobes to "exterior lights."

That's checklist customization done right: a takeoff briefing, the local transponder code and the clearance call are exactly what a student forgets. But customization has a dark side, and regulators know it.

That FAA warning, Safety Alert for Operators 17006 from April 2017, wasn't theoretical. It followed a gear-collapse accident in which an off-the-shelf checklist left out the steps for manually extending the landing gear.

The FAA Safety Team's January 2024 notice "A Check-up on Checklist Customization" sums up the US position. There is "no approval required from the FAA to modify or customize a checklist" for Part 91. But examiners may require the manufacturer's procedure on a checkride, and instructors should teach the items a custom list leaves out. As we showed in our Cessna 172M, N, P, R and S comparison, a "172 checklist" written for one model year can be dangerously wrong for another: carbureted vs fuel-injected starts, different flap limits, different glide speeds.

Memory vs reading: what belongs in your head

If checklists are so good, why memorize anything? Because some emergencies don't give you time to find a page. An engine failure at 300 feet after takeoff gives you seconds. The answer every regulator gives is the same: memorize as little as possible, and verify it against the checklist afterwards.

• FAA, AC 120-71B (2017): "Memory items should be avoided whenever possible." If used, they should be "less than three items" with no conditional decision steps.
• UK CAA, CAP 676 (2006): memory items go first on the checklist, boxed or shaded, "preferably fewer than four and certainly no more than six" for multi-crew operations. Single-pilot operations may need more.
• FAA Pilot's Handbook of Aeronautical Knowledge: memorize the immediate action items and, after completing them, refer to the appropriate checklist.
• FAA Private Pilot ACS: where reading a checklist would be unsafe, the examiner evaluates the memory items, then the checklist review "once conditions permit."

Now look at what happens in the real world. After the two Boeing 737 MAX accidents, the FAA's 2020 airworthiness directive rewrote the runaway stabilizer and unreliable airspeed procedures. Airline groups asked the FAA to simplify the recall items. The FAA refused, reasoning that merging steps "would increase the likelihood that a critical flightcrew action is forgotten." Southwest's pilots' union described the result as eight memory steps including three conditional ones. Compare that with the FAA's own advice: fewer than three, with no conditions. Some US airlines responded by moving the procedure onto a laminated Quick Reference Card.

Then there's the problem of how long a written checklist is. On 15 January 2009, US Airways 1549, an Airbus A320, hit a flock of geese at 2,818 feet above the ground and lost both engines. The crew had about three and a half minutes before they landed on the Hudson. Their Engine Dual Failure checklist had been designed for failures above 20,000 feet. It was three parts on three pages. According to the NTSB, the crew got as far as the middle of part one and "never reached the ditching portion." Everyone survived anyway. The NTSB called the checklist unduly long for such an event and recommended low-altitude dual-engine-failure checklists.

There's also startle to account for. A 2017 study by TNO and TU Delft put 20 airline pilots through stall recoveries. When the stall came as a surprise, they followed the recovery procedure significantly worse than when they expected it. EASA now requires startle and surprise training for airline pilots. The lesson for everyone else: a memory item you've never rehearsed under pressure isn't really a memory item.

For a light airplane, a sensible split looks like the POH's own engine failure checklist for a Cessna 172S. The first five lines are short, fixed and in the same order every time, so they're the ones worth committing to memory, highlighted here. The rest you read:

Memory aids such as GUMPS (gas, undercarriage, mixture, propeller, switches) before landing, or "airspeed, best field, checklist" after an engine failure, are useful flows. But they're backups to the written list, not replacements. A mnemonic doesn't know that your airplane has carb heat, or a fuel shutoff valve.

Paper vs glass in light airplanes

Walk down any flight line and you'll see three generations of checklist side by side.

The steam-gauge trainer. A 1970s Cessna 172M or Piper Warrior has nothing but the POH and whatever card the owner put in the side pocket. The checklist lives on paper, a kneeboard or a phone. It's simple and reliable. But paper has a known flaw that Degani and Wiener pointed out back in 1990: it gives you no mark of where you were interrupted, and it doesn't show which items you've done.

The glass trainer. Garmin's G1000 NXi can display checklists on the multifunction display. They're written with Garmin's Checklist Editor and loaded from an SD card. That's powerful, and Garmin attaches a pointed warning: "Do not use an unapproved checklist during flight operations." In many G1000 airplanes the electronic checklist is something the owner sets up, not something the manufacturer certifies.

The 2024 Cirrus. When Cirrus unveiled the SR-series G7 in January 2024, its Perspective Touch+ flight deck added touchscreen controllers and CAS-linked checklists: when the crew alerting system raises a caution, the avionics suggest the matching checklist, which the pilot can open or dismiss. There's a dedicated checklist scroll wheel too. Cirrus has since brought "alerts-linked checklists" to its Vision Jet. This is the airliner idea of an electronic checklist that knows what's wrong, arriving in a four-seat piston single.

Here's what that looks like in practice. Below is the before-landing checklist from the Cessna 172S G1000 POH, drawn the way a glass-cockpit display shows it. Tap CHECK to tick the item in the cyan box and move to the next, just as a pilot does with a touchscreen key or the ENT button on the panel:

Notice what the screen does that a laminated card can't. It shows exactly where you are and what's done, and it doesn't say "finished" until every line is green. If ATC calls halfway through, the cyan box is still waiting on the item you were on when you come back. On a Boeing 787 the sensed items turn green by themselves. In a light airplane, the pilot still confirms every line.

Whatever you use, carry a backup. EASA's guidance for private pilots says that when an electronic flight bag displays aircraft checklists, the pilot should check before flight that an appropriate backup is available. In the US, Advisory Circular 91-78A covers electronic flight bags, including checklists, for Part 91 pilots.

What airline pilots actually use: Boeing, Airbus, Embraer and ATR

So what does an airline transport pilot actually look at? It depends almost entirely on which airplane they fly. And the answer isn't always "a screen."

Boeing: the 737 is the odd one out

Boeing introduced its electronic checklist on the 777 in the mid-1990s, calling it the world's first airline-modifiable electronic checklist. The ECL runs on a centre display. Items Boeing calls "closed-loop" are sensed from switch positions and tick themselves off; "open-loop" items, which the airplane can't sense, are confirmed by the pilot with the cursor. Non-normal checklists are tied to the EICAS alert messages and sorted by priority, so a caution brings up its own procedure. FAA Advisory Circular 120-64 requires a paper version that leads to the same crew actions.

Does it work? Boeing's checklist chief Daniel Boorman reported that in an unpublished Boeing simulator study, crews made 46% fewer errors with the electronic checklist than with paper. He also estimated that a fully integrated electronic checklist could have prevented 19 accidents between 1978 and 2001. Those are Boeing's own figures, and the study was never published, but they fit decades-old human-reliability data: an item with no way to tick it off has an error rate of about 1 in 100, falling to about 3 in 1,000 when you physically check it off.

The 787 works the same way: the ECL senses control positions, non-sensed items are selected with the cursor, and the checklist is reset before every flight. The 747-8 brought "many of the advanced features found on the Boeing 777, such as an electronic checklist" to the jumbo.

The 737, the most-flown Boeing of all, still flies with a printed normal checklist and a paper Quick Reference Handbook, often supplemented by an iPad QRH. It is the only airplane Boeing still sells with no EICAS, which is why a 2020 US law requiring modern crew-alerting systems forced Congress to extend the deadline for the 737 MAX 7 and MAX 10.

Airbus: ECAM tells you what's wrong

Airbus took a different route. Since the A310 and A320 in the 1980s, the ECAM (Electronic Centralised Aircraft Monitor) has displayed the abnormal procedure for each failure on the upper central screen, as a list of actions that clears as they're done. Normal checklists on the A320, A330 and A340 are mostly read from a printed card, with the takeoff and landing "memos" on screen showing items still to do. Airbus's procedure is classic do-verify with challenge-response: the pilot flying completes the flow, calls for the checklist, the pilot monitoring reads it, and ends with "checklist complete."

On the A380 (2007) and A350 (2015), normal checklists also moved onto the screen: the pilot presses a "C/L" button and the engine and warning display shows the normal checklist. Airbus also sells an electronic QRH for tablets on its older families, which it called "the future of flight operations" in 2017.

ECAM's limits were exposed on Qantas 32, an A380 whose number 2 engine burst over Indonesia in November 2010. The crew faced a cascade of ECAM messages. Their captain later described about 100 checklists. The Australian Transport Safety Bureau found it took about 50 minutes just to complete the initial procedures. With five pilots on the flight deck, they landed everyone safely.

Embraer: EICAS and the tablet QRH

Embraer's E-Jets, flown by regional airlines across the US, Europe and beyond, show alerts on an EICAS display, with procedures in a Quick Reference Handbook. Embraer's iPad eQRH, launched in 2014 and now covering both E1 and E2 jets, is described as an interactive checklist meant to replace the paper QRH. In business aviation, Embraer goes further: its Praetor jets are marketed as paper-free flight decks with electronic checklists.

ATR 72-600: the regional workhorse

The ATR 72-600 is one of the most common turboprops at regional airlines from India to Scandinavia. India's IndiGo alone had 48 in mid-2025 and gave its ATR pilots iPad EFBs in 2024. Its Thales glass cockpit uses five large LCDs. ATR says the electronic procedures on the engine and warning display (EWD) "automatically pop-up the procedure needed at the right time." The 2017 Standard 3 avionics, certified by EASA in July 2017, added customizable checklists.

That's why TransAsia 235 is so sobering. On 4 February 2015, an ATR 72-600 had a fault on its right engine shortly after takeoff from Taipei. The display showed the engine flame-out procedure, and the airline's procedure was to read and do the QRH checklist. The monitoring pilot said "wait a second, cross check," but the pilot flying pulled back the throttle of the working left engine. Taiwan's Aviation Safety Council found the crew failed to perform the documented failure identification procedure. 43 of the 58 people on board died. The checklist was on the screen. Nobody read it.

FAA vs EASA vs ICAO: what the rules actually say

Ask ten pilots whether using a checklist is a legal requirement and you'll get ten answers. Here's what the rules actually say.

United States. For large airplanes, turbojet-powered multiengine airplanes and fractional ownership aircraft, 14 CFR 91.503 requires a cockpit checklist at the pilot station, used "by the flight crewmembers when operating the airplane." Airlines are covered by 14 CFR 121.315, which requires an approved cockpit check procedure designed so a crewmember "will not need to rely upon his memory for items to be checked." Part 135 operators must provide checklists, and pilots must use them (14 CFR 135.83). But no rule explicitly requires a Part 91 pilot in a light single to use a checklist. The FAA enforces it differently: the Private Pilot Airman Certification Standards include a dedicated "Use of Checklists" appendix, and nearly every task includes completing the appropriate checklist.

Europe. EASA puts it in the law itself. Under NCO.GEN.105(a)(3) of Part-NCO, the pilot in command of a non-commercial flight, including a private pilot in a Robin or a Cessna, is responsible for "ensuring that all operational procedures and checklists are complied with." The guidance attached to it says the pilot should use the manufacturer's latest checklists and restart interrupted pre-takeoff checks from a safe point. For airlines, ORO.GEN.110(h) requires a checklist for every aircraft type, and says its design and use "shall observe human factors principles." EASA's PPL skill test guidance says checks should be completed "in accordance with the authorised checklist."

ICAO. Annex 6 Part II requires checklists for larger general aviation aeroplanes (over 5,700 kg or turbojet), whose design must observe human factors principles. ICAO's design guidance, now in Doc 8168 Volume III, covers how to write one. Keep items to those critical to safety. Don't repeat a critical item more than twice. Define what to do after an interruption. Avoid "checked" as a response. Use colour coding (green normal, yellow abnormal, red emergency), but never colour alone.

The UK. The CAA's CAP 676 is still the most detailed guide to emergency checklist design. It says text should be readable at 600 mm, in a sans-serif font with 12 pt body text, one drill per page where possible, and memory items first. Its Good Airmanship leaflet is more relaxed for private flying: use the checklist "unless you are very familiar with the aircraft."

When the radio dies: why squawking 7600 isn't always enough

Every pilot learns the radio-failure drill early. Squawk 7600. Follow the lost-comms rules (in the US, 14 CFR 91.185 for IFR and 91.129(d) for landing at a towered airport; SERA.14083 in Europe). Watch the tower for light signals. It's on every checklist card, and on a checkride it's the answer that ticks the box.

It also rests on an assumption nobody prints on the card: that your transponder still works.

Code 7600 is a message sent by a box that needs electrical power, on the same bus as the radio it's reporting dead. Lose the alternator and then the battery, or a master relay, and the transponder goes dark along with the radios. So does ADS-B Out. There's nothing left to squawk. To the controller you're at best an unlabeled blip on primary radar, and down low, outside primary coverage, you may not be there at all.

ZuluCheck's founder learned this the hard way, when an electrical failure took out the radio and the transponder at the same time. The checklist answer, squawk 7600, assumed a box that had no power. "That's what's required" is a fine answer in a ground school. In the air, with no way to tell anyone who you are or what you want, it isn't a plan.

The rules themselves leave room for more. The FAA's Aeronautical Information Manual (AIM 6-4-1) admits it is "virtually impossible" to write procedures for every radio failure, says pilots are "expected to exercise good judgment," and reminds them of the emergency authority in 14 CFR 91.3(b). AIM 6-4-3 lists ways to get back in touch, from the last frequency to Flight Service and 121.5, and adds: "If the capability exists, do all at the same time."

The capability most pilots carry is in their pocket. A short phone call to the tower, approach or the area control centre turns a silent blip into a conversation. You can say who you are, where you are, what's wrong and what you want. You can get a clearance, an agreed route through the airspace or a green light from the tower, instead of hoping the controller guesses right.

Be clear-eyed about the limits:

• Fly first. Aviate, navigate, communicate. Make the call only when the airplane is stable and you can do it safely, and keep following the published procedure while you do.
• The FAA hasn't caught up. The AIM never mentions phones in flight, and the FCC's 47 CFR 22.925 bars using a cellphone in flight. Europe has: since May 2025, SERA.14083 tells pilots to try "all available means," mobile phones included. Either way, a lost-comms emergency is the case where pilot judgment comes first.
• Coverage is patchy. Cell signal is usually better low and near towns than high or over remote country.
• The hard part is the number. The right one is printed somewhere: in the US Chart Supplement, in your country's AIP, on a sticky note at home. That's no help at 2,000 feet with a dead panel and both hands busy.

That's the problem ZuluCheck solves. The frequency bar at the bottom of every checklist screen shows your local frequencies and 121.5. Tap it, and the radio-failure sheet opens: the phone numbers for the nearest aerodrome (from your location, or your home field), a backup ATC unit such as approach or the area control centre, and the rescue coordination centre. Each is one big button that dials with a single tap. The numbers are stored in the app, so the list appears even with no data signal, along with their source and date. They cover every public-use airport in the United States and the aerodromes of the UK, France and Israel so far, more than 5,000 in all.

If your headset pairs with your phone over Bluetooth, as many current aviation headsets do, the call comes through your ear cups, over the engine. Most Bluetooth headsets run on their own batteries, so they keep working when the panel doesn't.

A laminated card can't dial a phone. Neither, as far as we know, can any other checklist app.

For the full lost-comms procedures in the US, Europe, the UK and Israel, every light gun signal and the real incidents behind them, read our guide to lost comms and light gun signals.