in the UK
believe that a Turkish Airlines Boeing 737-800 pilot misinterpreted information
on a departure plate, resulting in the aircraft’s levelling off at extremely
low altitude after taking off from London Stansted.
flew for about 6nm (11km) at a height of just 500ft above the ground during the
incident on 16 October last year.
jet was operating a service to Istanbul
and had departed runway 05 with instructions to follow the standard instrument
departure pattern Dover Five Sierra.
Five Sierra involves a climb straight ahead to 850ft – equivalent to about
500ft above Stansted ground level – then a right turn
to a heading of 209°, with the aircraft maintaining a 5.5% climb gradient
before levelling off at 5,000ft.
the Turkish 737 instead levelled off within seconds of departing. London
area air traffic control contacted the crew and the pilot reported the jet’s
altitude as 900ft above sea level, below the minimum safe altitude of 1,800ft.
ordered the aircraft to climb immediately to 5,000ft and the aircraft proceeded
without further incident.
a bulletin on the event the Air Accidents Investigation Branch says the crew
had misunderstood the notes on the Stansted standard
instrument departure plate, apparently confusing the straight-ahead climb
instruction with the initial level-off altitude.
take-off the co-pilot had entered 900ft in the altitude pre-selector. Although
the captain had thought the figure unusual he did not seek clarification from
air traffic control.
the incident the commander realised that he and the co-pilot had not registered
the exact meaning of the ‘initial climb’ note on the SID plate and thought this
might have been due to a language issue,” says the AAIB.
states that the occurrence, the first of its kind on record in the UK,
was too rare to warrant a safety recommendation. But the AAIB also says the
crew was fortunate that visibility was good and the surrounding terrain was
[the aircraft] been in instrument meteorological conditions and operating from
an airport where terrain was more prevalent,” it says, “this incident could
have quickly become more serious.”