Communicating with other aircraft

[Nicholas49]

Hello

If the pilots of an aircraft want to communicate with those of another one (for example, when waiting in line for take-off you notice something untoward about the aircraft ahead of you that you want to alert its pilots to), are you allowed to speak to them directly over the radio or must you communicate through ATC?

If the answer is 'always through ATC' but you felt there was a real risk that the message may not get across for whatever reason, would you then speak directly?

Thanks
Nick

[99jolegg]

You always speak to ATC. if they're on the same frequency as you they'll probably have heard you and will know you're addressing them. In that case, I'm sure the ground unit would just confirm that the message has been received.

That said, if you saw an issue that was a threat to safety and ATC weren't understanding (abroad) you then you're hardly going to let them depart - you'd tell them on the radio and let them decide.

[DavidWoodward]

I've had one or two different occasions where someone has passed a message to me via ATC. It's normal practice to do so and ATC like to be aware of exactly what's going on.

[hvogt]

I have been thinking about this question for a while, but never bothered to look up the answer. Whenever I wanted to contact another aircraft I have asked ATC for permission. Usually, I would say something like "<call sign> request interpilot transmission with <other call sign>". It seems this approach is in line with the respective ICAO standard (5.1.7 of ICAO Annex 10, Volume 2):
In communication between aircraft stations, the duration of communication shall be controlled by the aircraft station which is receiving, subject to the intervention of an aeronautical station. If such communications take place on an ATS frequency, prior permission of the aeronautical station shall be obtained. Such requests for permission are not required for brief exchanges.

[denachtenmai]

ISTR something between an A/c following a Lufthansa 74 and the following A/c called to the LH over the atc freq. go to 123.4 or some discrete freq.
LH replied "we only communicate on atc freq.:rolleyes:
OK said following, "Your ground locks are in":eek:
Regards, Den.