what happens if ?

[boe777]

Imagine an Aircraft in the vicinity of a major Airport or in a stack and has a radio communication failure, what happens then, how would that aircraft be guided along the approach within the Q of traffic already on approach ?
ie: if ATC does not get any aknowledgement from the aircraft, at what point the alarm bells start ringing...and what would be the procedure on behalf of ATC and Aircraft to land safely.

the question may sound daft with my limited knowledge, can anyone explain.

[HEATHROW DIRECTOR]

There are quite specific procedures laid down for pilots and ATC to follow in the event of communication failure. Landing charts are published for the vast majority of airfields and, in the event of radio failure, the pilot would carry out the procedures as promulgated. ATC would ensure that other aircraft were separated from the one experiencing radio failure until a safe landing had been carried out.

It doesn't happen very often but it's not a major problem.

[boe777]

Thanks HD,

At what point the pilot would know that it is Okay to make the approach, as there may be many Aircrafts in the stack, is there a number of times that ATC would try to communicate after which they would make the decision to get other aircrafts out of the way ?

[dazdaz]

If I was the pilot I'd use a mobile phone. Unfortunately I'm not a pilot so this might seem a bit simplistic.

[boe777]

provided he has GSM and knows the number of ATC heathrow hotline ?
who knows they might have such a thing...

[leewan]

Here, the a/c has to be flown to a designated holding point once the pilot realizes he has a radio failure. Later on, I presume they will send in a " Follow- Me" plane to guide the a/c down.

[HEATHROW DIRECTOR]

Look.... first of all, an aircraft may be flown half-way round the world without talking to anyone. Radio navigation aids, inertial systems, GPS, Instrument Landing Systems and similar equipment allow the aircraft to be navigated accurately and to land safely in the event of a radio failure.

ATC will be fully aware of the problem and they know the procedures which the pilot will follow. Exact procedures vary depending on the destination airport but, for example, they might state that the aircraft should maintain it's last assigned altitude... fly to the holding point associated with the destination airfield... descend in that holding pattern over a period of x minutes and then commence approach. Every holding point has an approach procedure associated with it so everyone knows what the pilot will do. ATC simply keep other aircraft clear of the one with comms failure... That, in very basic terms, is what happens.

It's no big deal for properly trained pilots and controllers..

dazdaz....... you stay with your acting job!!!

Here's part of the UK procedures, all of which are available in the public domain:

4.2.4.1 A flight experiencing communication failure in IMC shall:
(a) Operate secondary radar transponder on Mode A, Code 7600 with Mode C.
(b) (i) Maintain, for a period of 7 minutes, the current speed and last assigned level or minimum safe altitude, if this higher.
The period of seven minutes begins when the transponder is set to 7600 and this should be done as soon as the pilot
has detected communications failure.
(ii) If failure occurs when the aircraft is following a notified departure procedure such as a Standard Instrument Departure
(SID) and clearance to climb, or re-routing instructions have not been given, the procedure should be flown in
accordance with the published lateral track and vertical profile, including any stepped climbs, until the last position, fix,
or waypoint, published for the procedure, has been reached. Then, for that part of the period of 7 minutes that may
remain, maintain the current speed and last assigned level or minimum safe altitude, if this higher.
(iii) Thereafter, adjust the speed and level in accordance with the current flight plan and continue the flight to the
appropriate designated landing aid serving the destination aerodrome. Attempt to transmit position reports and
altitude/flight level on the appropriate frequency when over routine reporting points.
(c) (i) If being radar vectored, or proceeding offset according to RNAV, without a specified limit, continue in accordance with
ATC instructions last acknowledged for 3 minutes only and then proceed in the most direct manner possible to rejoin
the current flight planned route. Pilots should ensure that they remain at, or above, the minimum safe altitude.
(ii) If being radar vectored by an Approach Control Radar Unit (callsign DIRECTOR/RADAR/APPROACH), comply with the
loss of communications procedures notified on the appropriate ATC Surveillance Minimum Altitude Chart (ATCSMAC)
as detailed in the AD 2 section of the UK AIP.
(d) (i) Arrange the flight to arrive over the appropriate designated landing aid serving the destination aerodrome as closely as
possible to the ETA last acknowledged by ATC. If no such ETA has been acknowledged, the pilot should use an ETA
derived from the last acknowledged position report and the flight-planned times for the subsequent sections of the flight.
(ii) Arrange the flight to arrive over the appropriate designated landing aid serving the destination aerodrome at the highest
notified Minimum Sector Altitude taking account of en-route terrain clearance requirements.
(iii) If following a notified Standard Arrival Route (STAR), after the seven minute period detailed in paragraph (b) (i) has
been completed, pilots should arrange descent as close as possible to the published descent planning profile. If no
descent profile is published, pilots should arrange descent to be at the minimum published level at the appropriate
designated Initial Approach fix.
(e) On reaching the appropriate designated landing aid serving the destination aerodrome, begin further descent at the last
acknowledged EAT. If no EAT has been acknowledged, the descent should be started at the ETA calculated in (d) (i),
above, or as close as possible to this time. If necessary, remain within the holding pattern until the minimum holding level,
published for the facility, has been reached. The rate of descent in holding patterns should not be less than 500 ft per
minute. If 'Delay not determined' has been given, do not attempt to land at the destination aerodrome, divert to the alternate
destination specified in the current flight plan or another suitable airfield.
(f) Carry out the notified instrument approach procedure as specified for the designated navigational aid and, if possible, land
within 30 minutes of the EAT or the calculated ETA. When practical, pilots should take account of visual landing aids and
keep watch for instructions that may be issued by visual signals from the ground.
(g) If communications failure occurs during an approach directed by radar, continue visually, or by using an alternative aid. If
this is not practical, carry out the missed approach procedure and continue to a holding facility appropriate to the airfield of
intended landing for which an instrument approach is notified and then carry out that procedure.

Etc, etc, etc.......

[boe777]

HD,

Maintaining the FL and designated holding area in case of trouble makes sense, so the pilot will presume that after the last contact x minutes and i should start to make an approach over the designated path for landing .

Did you in your career encounter anything like that at heathrow ? of course you dont have to give specifics..


Thanks

[HEATHROW DIRECTOR]

boe777... Yes, I encountered aircraft experiencing radio failure on a number of occasions. It really is not a major problem except that there may be a short delay to subsequent aircraft as ATC, not knowing the precise track which the radio failure aircraft will fly, will leave plenty of room from other traffic.