Formation/Combine Operations...

[engineoff]

I'm interested to hear in the legality of usage of 'combine' and formation callsigns.. We have previously operated simply with the lead aircraft carrying out the radio calls using his callsign followed by 'combine' to indicate more than one aircraft. This has been used on numerous occasions including departure/arrival procedures from controlled airfields.
Is this ok for us to simply modify our callsign in this way and are group clearances in this way acceptable or is this a grey area. I am thinking along the lines of if an error were to be made by one of the formation aircraft and responsibility for clearances.
Also with a group of aircraft is the preferred method with ATC for the lead aircraft to squawk conspicuity or an assigned code and the following aircraft to leave their transponders on standby?

[Chilli Monster]

I've worked several 'combines' who were following the procedures you describe and have no problem with them at all. The only thing that does concern me is frequency changes. How do you know no.2 has heard correctly? The military way of the leader restating the frequency and then executing the change goes part way there, but you still don't know whether no.2 has heard the new freq correctly. Still - that's something for the formation to discuss in their procedures brief before the flight.

As for the transponder - yes, lead squawks either VFR or assigned squawk and others squawk standby, otherwise you just end up with a garbled mess on the display.

[The Jaguar Fan Club]

CM

Just to clarify, the norm is for all aircarft in a formation to squawk Mode A & C unless all aircraft are within 1 nm and co- level with the leader, when they would squawk standby. This is to prevent unecessary avoiding action being taken against non-squawking formation elements that may be laterally displaced from the leader. Remember many formations can be split by a couple of miles (battle, card etc).

My advice would be to use the suffix "formation" only if flying and maintaining a recognised or close formation with other aircraft. If you are just randomly following each other on a trip somewhere, "combine" may be better to reduce RT loading where you are doing the same thing.

Cheers
TJFC

[aluminium persuader]

If I remember rightly, a flight of more than one a/c may only be treated as a formation if all the components are within 1nm, and only the lead a/c should squawk. Outside of a mile, you need authorisation to operate as a formation (from whom, I don't know - I guess the CAA), and the lead & trail a/c squawk. Calling yourself "combine" is still a formation callsign and should be treated in the same manner. If the a/c are "some distance apart", you should use individual callsigns as you are independant units.

Regarding the suffix -

xxx pair = 2 a/c of same type (eg 2x gazelles)

xxx combine = 2 or more a/c of more than one type (eg 1Lynx +1Gazelle)

xxx formation = more than 2 a/c of same type

Hope this helps.

:)

(edited cos I forgot some stuff!)