Squawk 7500

[DFS346]

Does anyone know or remember when 7500 became, or was designated, the standard transponder code for a hijacking?

[Dan Dare]

Before my time, but I do remember when we didn't talk about that "assigned code" and although it is probably a fairly open secret and would appear on every spotter-scope instantly, it still doesn't feel right talking about it.

[DaveReidUK]

Originally Posted by Dan Dare

although it is probably a fairly open secret and would appear on every spotter-scope instantly, it still doesn't feel right talking about it.

It's not a secret at all, open or otherwise.

US$330 from the ICAO Shop:

[DFS346]

Many thanks. Found partial answer in ICAO Annex 11,

Amendment 23: use of SSR code 7500 in the event of unlawful interference; requirements for communications between ATS units and meteorological offices. Adopted/approved 12 December 1975; effective 12 April 1976; applicable 12 August 1976.

​​​​​​​So 7500 was in use by December 1975; but it's not clear when it came into effect for communications between flight crew and ATS.

[Phileas Fogg]

Originally Posted by DFS346

Many thanks. Found partial answer in ICAO Annex 11,

Amendment 23: use of SSR code 7500 in the event of unlawful interference; requirements for communications between ATS units and meteorological offices. Adopted/approved 12 December 1975; effective 12 April 1976; applicable 12 August 1976.

​​​​​​​So 7500 was in use by December 1975; but it's not clear when it came into effect for communications between flight crew and ATS.

Well I did my RAF Air Traffic Control training in Aug/Sep 1976 and the 7500, 7600 & 7700 transponder codes were in our training

[sheepless]

In 1976 or 1977 (I forget the exact year) the code in the UK changed from 3100 to 7500. I remember the day it changed well. The first flight I had from Humberside to Amsterdam was allocated code 3100 by LATCC. I passed it to the Air Angila flight who took it without question. Some hours later the pilot phoned from Amsterdam wanting to know why I had given him the Hijack code. Apparently Amsterdam made him number 1 with a straight in approach (this was during the morning rush). After landing he was directed to a remote stand and the aircraft was surrounded by the military. Although the code had changed at midnight no one had reset the Amsterdam computer to recognise the new code so HJACK appeared in the radar label.

[chevvron]

Originally Posted by DFS346

Does anyone know or remember when 7500 became, or was designated, the standard transponder code for a hijacking?

As far as I recall, all 3 main special purpose codes (7500, 7600 and 7700) were introduced at the same time.

[chevvron]

We had a procedure in the UK whereby if a certain code came up, the controller was to say 'confirm squawking assigned code?'

[dixi188]

When training in the USA in 1990 we were told of a procedure to leave something non standard when taxiing in to denote hijack. Not saying what in case this is still the case.

[grizzled]

Originally Posted by dixi188

When training in the USA in 1990 we were told of a procedure to leave something non standard when taxiing in to denote hijack. Not saying what in case this is still the case.

Regulators and ATC (and I assume some air carriers) in some countries still refer to this in training, or in the case of ATC, as a confidential ops memo. It's now problematic, as it seems air crew are no longer routinely taught the item. As it's no longer widely known, ATC likely would not even notice, or would not know what phraseolgy to use if they did notice. 'Nuff said

[DFS346]

Found an answer specific to the U.S. in the FAA Airman's Information Manual, May 1976: the ATC code for hijack changed from 3100 to 7500 effective September 9, 1976.