Thomas Cook holiday flight in ‘serious’ incident at Manchester Airport after pilot underestimated take-off weight by 17 tonnes

On 29th April, a holiday flight taking off from Manchester airport nearly had serious problems when the pilot and co-pilot read the wrong reading, and therefore understimated the take off weight of the plane (not adding the weight of the 17 tonnes of fuel). This meant they wrongly calculated the thrust needed for take off, and tried to take off at too low a speed. This could have caused problems, including in control of the aircraft.


8.12.2011  (Manchester Evening News)

A holiday flight with 223 passengers on board took off using insufficient thrust and speed after a mistake by the captain about the plane’s weight, an accident report revealed today.

The Airbus A321 operated by Thomas Cook was 17,000kg (17 tonnes) heavier on take-off than the figure the cockpit crew used to calculate their take-off performance, the report by the Air Accidents Investigation Branch (AAIB) said.

Before the flight, from Manchester to Heraklion in Crete, the co-pilot had asked the captain for the take-off weight.

In what was described as a serious incident, the report said: “The captain had read out what he thought was the actual take-off mass (Atom) but mistakenly read out the zero fuel mass (ZFM) of 69,638kg.”

The report said the flight management system had been programmed “with the incorrect speeds” in the incident which took place on the morning of April 29 this year – the day of wedding of the Duke and Duchess of Cambridge.

The report went on: “The aircraft took off using less thrust and lower reference speed than were required.

“The effect of the attempted rotation at too slow a speed was noticeable to the PF (the pilot flying the plane) through the feel of the aircraft and the displays on the speed scale.

“He responded by reducing the pitch attitude, which allowed the aircraft to accelerate to a safe climb speed.”

The AAIB said there were “a number of errors that occurred” but the first was the misreading of the ZFM by the captain.

The report said that “from an early stage, both pilots were using incorrect data” and that “later, there were a number of missed opportunities to detect the error through the SOPs (standard operating procedures)”.

The AAIB went on: “A take-off with inadequate thrust and speed could lead to a loss of control of the aircraft.”

It added that the plane’s operator had stressed to its crews, through the issue of a flight safety bulletin, the importance of accurate performance calculations and had also made other changes to procedures.

The AAIB revealed that in November 2009 it had made two safety recommendations to the European Aviation Safety Agency (Easa) concerning take-off performance monitoring systems following an incident involving an Airbus A330.

The AAIB added: “The Easa has not yet accepted these safety recommendations but they are under consideration.”

Today’s report said there had a been “a significant number of reported incidents and several accidents resulting from errors in take-off performance calculations around the world in recent years”.

It went on: “There must also have been many similar events which were either unreported and/or unnoticed, some of which will have had the potential to cause accidents.”

The AAIB said several studies of these events had been carried out including ones by Australian and French investigators.

Today’s report went on: “Many errors which occur are successfully detected but there is no single solution to ensure that such errors are always prevented or captured.

“Industry awareness of the frequency of these errors has been raised but a solution has yet to be found.”

The AAIB added that take-off performance monitoring systems, recommended to Easa, “would provide an alert to the flight crew if a take-off was not progressing as expected”.