STANDARD INSTRUMENT DEPARTURES AT HEATHROW

With the volume of traffic involved it would be impossible for every pilot to be given an individual flight clearance over the radio - the airwaves would soon become clogged with controllers and pilots trying to pass messages to each other. In order to relieve airband congestion, the various departures for aircraft leaving busy airports have been classified into specific routes, known as Standard Instrument Departures (or SIDs).

At Heathrow, there are eight Standard Instrument Departure Routes in operation, namely Brookmans Park, Compton, Buzad Dover, Mayfield , Midhurst, Southampton and Woburn. Other major airfields have separate SIDs under the same system. The SID will be given a number and a letter as part of its identification and at Heathrow the last character indicates the departure runway which is being used at the time. Runway 27R is indicated by the letter F, 27L has the letter G, 09R letter J, 09L letter K, 05 letter L and 23 letter H. In the example which follows, the runway in use is 27R.

When a pilot initially calls the Ground Movement Planner, he/she will be aware of the SID to be followed and ATC will confirm the clearance. In the first message the pilot will also quote the stand at which the aircraft is parked, and the weather details taken from a recorded broadcast - in this case ‘BRAVO’.

The reply from ATC will specify the SID and also the secondary radar identify ‘squawk’ code. For example:

Pilot: Heathrow Ground, Speedbird 283 at Tango with BRAVO, request start-up.

ATC: Speedbird 283 good afternoon, your clearance is to Los Angeles, Daventry One Foxtrot departure, squawk 4136.

Pilot: Roger, 283 cleared to start, Daventry one Foxtrot, squawk 4136.

ATC: That's correct, Sir, Ground now on 121.9.

The ‘BRAVO’ information is the current terminal information in use. When the details change, the new tape will be designated with the next letter of the alphabet - in this case ‘Charlie’. Routes to airports are known as STARS (Standard Arrivals).

2. Answer the questions to the text above.

a) How many runways are there at Heathrow airport?

How are they indicated in SIDs?

b) Which does the pilot's first message consist of?

c) What does the ATC reply specify?

d) Why were the departures for aircraft leaving busy airports classified into Standard Instrument Departures?