Created Saturday, Oct 10th 2020 11:38Z, last updated Wednesday, Dec 23rd 2020 14:30Z
A Lufthansa Cargo Boeing 777-200 freighter, registration D-ALFG performing flight GEC-8402 from Frankfurt/Main (Germany) to Shanghai Pudong (China) with 4 crew, was in the initial climb out of Frankfurt's runway 25C when the crew declared Mayday, Mayday reporting unreliable airspeed. The crew subsequenty inquired with ATC what their altitude readings were, the controller responded 200 feet. The crew reported their standby altimeter was indicating 6100 feet and according to GPS they were at 6200 feet, so they should be around that altitude. The crew decided to return to Frankfurt and requested to dump fuel. The aircraft dumped fuel and returned to Frankfurt for a safe landing on runway 07C about 65 minutes after departure.
According to ADS-B data transmitted by the aircraft the aircraft did not climb above 250 feet throughout the entire flight.
On Dec 23rd 2020 Germany's BFU reported the sensors of the left and right static system had not been connected. The occurrence was rated a serious incident and is being investigated by the BFU.
In their October Bulletin the BFU reported the aircraft had undergone maintenance in the days prior to the occurrence, during which - amongst others - the connecting pipes of the static systems were flushed with dry air followed by leak tests and a system test.
The first officer (42, ATPL) was pilot flying, the captain (44, ATPL) was pilot monitoring. In addition a secondary captain (56, ATPL) and another first officer (43, ATPL) were on board.
The BFU reported the aircraft departed runway 25C and took off at 204 KIAS (191 knots over ground). About 15 seconds a wind shear warning occurred (recorded by both FDR and CVR) with 176 KIAS and 199 knots over ground. The first officer commanded "max thrust", the commander acknowledged and informed ATC about the windshear stating they now had 50 knots of wind on their tail. The first officer gradually reduced the pitch from about 11 to 7 degrees, the captain instructed to increase the pitch again, the first officer pointed at the airspeed and stated she didn't want to go slow (178 KIAS indicated at that time). The captain was puzzled as the tail wind component indicated was now 80 knots and despite maximum thrust it was not possible to increase the airspeed. When the tail wind increased to 100 knots, the commander concluded "this looks odd to me, I conclude this is unreliable airspeed." The captain took control of the aircraft, the first officer assumed the role as pilot monitoring. Shortly after the first officer noticed the integrated standby flight display (ISFD) showed 300 KIAS, the FDR recorded a speed over ground of 300 knots at the same time. Both crew concluded this was unreliable airspeed, the captain decided to declare emergency and to fly the aircraft according to pitch and power. At that time the aircraft was at about 6000 feet MSL. According to the CVR the aircraft maintained between 6000 and 8000 feet MSL throughout most of the flight. The aircraft dumped fuel and returned for an ILS approach to runway 07C which concluded in a safe landing.
During the maintenance work two licensed aircraft mechanics were working, one was responsible to carry out the works, the other to independently verify the works had been done correctly. The work cards showed the tasks for the left and right hand static system had been carried out, and had been stamped tested without anomalies. A day later the center static system (stand by system) was worked, these works were carried out correctly.
The not connected static port lines (Photo: BFU):
