Russian investigators have disclosed further details about a spate of unreliable airspeed incidents involving Sukhoi Superjet 100s at Moscow Sheremetyevo.
All seven incidents involved Aeroflot flights departing the airport on 4-5 February.
The incidents affected seven different aircraft, according to an air safety bulletin from the Interstate Aviation Committee and transport supervisor Rostransnadzor.
Crews of three aircraft – RA-89046, RA-89061 and RA-89044 – respectively bound for Volgograd, Minsk and Anapa, aborted their take-off roll, at speeds ranging from 70-120kt.
Two other aircraft – RA-89027 to Arkhangelsk and RA-89106 to Platov – were climbing at relatively low heights of 600-1,200m, when the pilots experienced unreliable airspeed readings.
In the case of the Platov flight, the investigators also state that crews also had problems with the autothrottle and autopilot. Both services returned to Sheremetyevo.
The other two incidents occurred at higher altitudes, with RA-89014 to Dresden, which had speed display issues at 7,000ft, and RA-89062 to Chelyabinsk which showed a speed discrepancy at 33,000ft. These aircraft also returned to Sheremetyevo.
Sukhoi's civil aircraft division had previously defended the Superjet, stating that Sheremetyevo had been subjected to severe winter weather at the time, and other aircraft types had been affected.
Investigators have disclosed that on 4 February an Aeroflot A320 (VQ-BRW) out of Sheremetyevo, bound for Istanbul at 20,000ft, had speed indication issues, and the crew diverted to St Petersburg.
Inquiries are continuing into the fatal crash of a Saratov Airlines Antonov An-148 departing Moscow Domodedovo on 11 February, already linked to unreliable airspeed data after take-off.