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A ship at sea would fly its flag upside down to signal it's in distress. How does a plane or airliner that has no radio or transponder visually signal that it is in distress?

This question: How do commercial pilots send distress signals? explains how it is done using a radio or transponder, but how could the message "please don't shoot me down" be relayed visually to a fighter pilot?

Glorfindel
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Muze
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    To fly a flag upside down the aircraft would probably have to fly inverted :D "Look at me I'm in distress, I'm inverted" LOL – Jan Jun 02 '19 at 19:41
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    A flag upside down? Wouldn't do much good for Romania, France, Belgium and Japan, would it? – Mast Jun 03 '19 at 05:47
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    It seems like there are multiple questions here. Are you meaning specifically to ask about how to communicate with a fighter pilot who is escorting you if you've lost your radios or are you asking more generally about how to signal distress. It would be better to focus the question on one or the other, as this seems to be causing confusion in the answers. – reirab Jun 03 '19 at 06:12
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    @Mast That's some very impressive flag knowledge. Username checks out. – Cloud Jun 03 '19 at 10:35
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    I'm trying to imagine a situation in which "please don't shoot me down" would ever be a useful message ;-D – Aaron F Jun 03 '19 at 14:14
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    I remember a stolen MIG indicating a desire to land by dropping its landing gear at a South Korean base, but that wasn't distress. – Criggie Jun 03 '19 at 16:40
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    Annex IV of the "International Regulations for Preventing Collisions at Sea" (a.k.a., "COLREGS") lists fifteen different things that the crew of a ship can do to signal a dire emergency. Flying an up-side down flag is not one of them. – Solomon Slow Jun 03 '19 at 17:18
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    I would presume that every aircraft wants to communicate that particular message. – chrylis -cautiouslyoptimistic- Jun 03 '19 at 20:52
  • Once we got into trouble on a French ship, so we flew our flag upside down. Nobody helped. Then we flagged British and had another problem. We were ignored by 11 ships until a boat of British vexillologists stopped to help. Then we flagged American, ditto. Everybody stopped! – Harper - Reinstate Monica Jun 04 '19 at 09:29
  • Presumably, a plane could plummet towards the ground at high speeds to signal distress. – Monica Apologists Get Out Jun 04 '19 at 19:14
  • Have you tried pleading and praying? At this point of time, if you do not know how to follow the military aircraft and cannot communicate using radio or you lights a prayer is all I would have left. – Lumis Jun 05 '19 at 13:03

3 Answers3

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For the US, the FAA's Intercept Procedures list several things a pilot can indicate without radios:

  • Acknowledge instructions: rock wings, flash nav lights
  • Unable to land at indicated airport: flash landing lights
  • Cannot comply: switch all lights on and off at regular intervals
  • In distress: switch all lights on and off at irregular intervals
Pondlife
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  • Are the any other ways if those cannot be performed? – Muze Jun 02 '19 at 17:59
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    Being creative: If near enough, sheets of paper with one big letter on each? A torch or mirror? Cellphone if low enough (normally a nogo, but if in distress...). – Peter Jun 02 '19 at 19:31
  • @Peter Yes a satellite phone. – Muze Jun 02 '19 at 19:38
  • @Muze Handheld radio, mobile phone, gestures, Morse code with a flashlight, writing in large letters on a sheet of paper, and who knows what else. I'm guessing that people will get creative in that situation :-) – Pondlife Jun 02 '19 at 19:46
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    I dimly remember that flying in a triangular pattern is supposed to be a distress signal for ATC radar. – John K Jun 02 '19 at 23:45
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    @JohnK See this question :-) – Pondlife Jun 03 '19 at 00:18
  • Although not a commercial pilot example, during Operation Frequent Wind (US evacuation from Saigon during Vietnam War) "(...)the pilot of an RVNAF Cessna O-1 dropped a note on the deck of the carrier. The note read "Can you move these helicopter to the other side, I can land on your runway, I can fly 1 hour more, we have enough time to move. Please rescue me. Major Buang, Wife and 5 child." – Mark Jun 03 '19 at 05:14
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    @Peter I'm guessing you're in the UK? The thought of signaling with a torch while flying an airplane sounds like a very bad idea in American English. - haha – reirab Jun 03 '19 at 06:15
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    For your convenience „flashlight“. I‘m not a native speaker. – Peter Jun 03 '19 at 06:19
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    @Peter haha - Yeah, I knew what you meant. It just caused a funny mental picture. I suppose flames in the cockpit would be very effective at signalling distress, though. – reirab Jun 03 '19 at 06:26
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    I seen footage of planes in the 2WW waggling/rocking their wings to mean they're in need of help + don't shoot. In more modern films where a 'goodie' is flying back home in a stolen enemy aircraft - flying on a steady path, and rocking wings has been used to portray the 'don't shoot' - but obviously that's films, so pinch of salt needed. – Smock Jun 03 '19 at 10:12
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    @Peter "torch" is actually correct in British English; "flashlight" in American English :) – Muzer Jun 03 '19 at 11:03
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    Oh dear. So the trigger-happy interceptor pilot is supposed to know if the lights are flashing at a "regular" or "irregular" interval? Maybe the pilot being intercepted should hold up a box of Pepto-Bismol or Immodium. – quiet flyer Jun 09 '19 at 21:48
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ICAO describes the following distress signals in Annex 2 (Rules of the Air):

The following signals, used either together or separately, mean that grave and imminent danger threatens, and immediate assistance is requested:

a) a signal made by radiotelegraphy or by any other signalling method consisting of the group SOS (. . . — — — . . . in the Morse Code);

b) a radiotelephony distress signal consisting of the spoken word MAYDAY;

c) a distress message sent via data link which transmits the intent of the word MAYDAY;

d) rockets or shells throwing red lights, fired one at a time at short intervals;

e) a parachute flare showing a red light.

Note that a) mentions "any other signalling method", which could, for instance, be flashing aircraft lights. d) and e) require no radio or transponder.

In addition, the following urgency signals exist:

The following signals, used either together or separately, mean that an aircraft wishes to give notice of difficulties which compel it to land without requiring immediate assistance:

a) the repeated switching on and off of the landing lights;

b) the repeated switching on and off of the navigation lights in such manner as to be distinct from flashing navigation lights

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    Are there any signals which could be sent from an aircraft which lost all electrical systems? (I'm assuming most planes don't carry flares or rockets.) – Skyler Jun 03 '19 at 15:22
  • @Skyler In that case, rocking the wings could still be useful on short range. – Ferrybig Jun 04 '19 at 07:16
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    @Skyler: "...a [SOS] signal made by radiotelegraphy or by any other signalling method..." -- Interceptors will attempt to get a look into the cockpit for an idea of what's going on. A torch or smartphone light will do nicely. – DevSolar Jun 04 '19 at 15:29
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Commercial flights are very regular throughout the world. One sure fire way to signal "don't shoot me I'm in distress" would be to fly low, and slow. a 737 at 5000 AGL would certainly signal something is wrong (most of the time) and would certainly get someone's attention.

Finding an airport and following the failed comms procedures and making a landing there would also be a sure sign that you needed help.

Remember you don't need a transponder and radio to land, and if you're doing something unusual, generally speaking, everyone else gets out of the way. Also, it would depend on the kind of distress your in. With no radio and no transponder, you probably have a pretty big electrical issue and need to land right away. So land.

coteyr
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    Your advice goes against the procedure linked to in Pondlife's answer, which says: "Do not adjust your altitude, heading, or airspeed until directed to by the intercepting aircraft." – Tanner Swett Jun 03 '19 at 05:29
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    Those rules are for being intercepted. i.e. a fighter escort. I was speaking to letting others know you're in trouble. – coteyr Jun 03 '19 at 05:31
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    Yeah, I think the question isn't very clear about exactly what it's asking for. This seems to answer the title question, but not the part in the body about, "how could the message "please don't shoot me down" be relayed visually to a fighter pilot?" That part would indeed imply being escorted. Having said that, if your goal is to indicate that you are not a threat and should not be shot down, flying a 737 at 5,000 ft probably isn't the best first move. It will signal distress alright, but not so much the "Please don't shoot me down" part. – reirab Jun 03 '19 at 06:10
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    I think the downvoted are for suggesting flying a 737 at 5000 ft to get attention. While it would get you attention, I think it’s also a good way of getting shot down. – Notts90 Jun 03 '19 at 12:03
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    @reirab Why would you need to signal to your own escorts to not shoot you down? You'd signal that to interceptors if anything. – Kapten-N Jun 03 '19 at 12:29
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    @Kapten-N: I think the question here is to turn the interceptors (which would have to take into account the possibility of a 9/11 type of situation) into escorts (i.e. pilots who no longer wonder whether they will have to shoot you down, and instead attempt to help, e.g. by relaying morsed light signals to ground). – DevSolar Jun 04 '19 at 15:33
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    @DevSolar Yes. That was my point exactly. You're trying to signal interceptors, not escorts. – Kapten-N Jun 05 '19 at 19:11