Gripen Main Landing Gear Damaged During Unstabalised Short Field Landing
On 13 June 2018 a a Swedish Air Force Saab JAS 39 Gripen attempted a short-runway landing at Piteå Airfield during a military exercise. The approach was however unstabalised and the aircraft touched down hard and one main landing gear was damaged. The pilot aborted the landing and returned to Luleå/Kallax.
Damaged Swedish Saab JAS39C Gripen (Credit: Swedish Armed Forces via SHK)
The Swedish Accident Investigation Board (the Statens Haverikommission [SHK]) say in their safety investigation report (published in Swedish) that:
The hard touch down was caused by a too steep approach angle, tailwind and low speed before setting.
The damage…was due to an overload…caused by a too high rate of descend in relation to the aircraft mass in combination with a high nose-up attitude at touch down.
The damage components included a burst tyre, the right MLG side-stay locking mechanism, actuator and adjacent structure.
Damaged to MLG of Swedish Saab JAS39C Gripen (Credit: Swedish Armed Forces via SHK)
Damaged Sidestay Lock Mechanism of Swedish Saab JAS39C Gripen (Credit: via SHK)
Investigators found that at a number of landings on the first day of the exercise were “very close to the runway edge”, by which they appear to mean the runway end.
Background
Bas 90 (Flygbassystem 90, Air Base System 90) was dispersed operating base concept used by the Swedish Air Force during the Cold War. Bas 90 was developed during the 1970s and 1980s from the earlier Bas 60 concept and involves runways and taxiways that coincided with local roads .
BAS90 airfield (Credit: Land Survey via SHK)
The concept influenced the Gripen’s design (along with maintenance simplicity to suit a conscript level of experience, working at these dispersed sites). While the earlier Saab JA37 Viggen had reverse thrust for short field landings, the Gripen featured nose wheel braking and its effectiveness would be further enhanced by foreplane down force.
The Airfield
Piteå however was a civilian general aviation airfield and marked differently to a BAS90 site. They SHK comment:
Piteå Airport [sic]…had not been used previously for short-runway landings. It does not have a military classification and differs in execution from the military classified runways previously practised against, among other things, in length and placement of the threshold markings.
Piteå Airfield (Credit Piteå
Flying Club via SHK)The threshold marking at Piteå Airport was located 39.5 metres from the runway edge, which differs significantly from the short-runways previously used [typically 200 metres at a BAS90 site].
A site reconnaissance had been conducted but “without an established method” and so “vital information was not communicated to the squadron’s pilots”.
SHK Conclusions
The incident was caused by the landing being completed despite the fact that the approach was not stabilized and that it ended with a too steep approach angle.
Contributing facts were the absence of clear criteria for abort landing in case the flight was not stabilized at a certain point during the approach.
SHK Safety Recommendations
The SHK recommended the Armed Forces:
- Introduce clear criteria for when a short-runway landing should normally be aborted. (RM 2019:01 R1)
- Develop and establish a method for producing decision-making documentation for the use of short-runways and runways that are not militarily classified, in order to ensure that conditions relevant to the security [safety] on such runways are discovered and that information about them is conveyed to the air operations. (RM 2019:01 R2)
Other Safety Resources
- Military Airprox in Sweden A near mid air collision between a Swedish Gripen and Norwegian F-16 during the 2015 Arctic Fighter Meet. The aircraft were ~ 30m apart in cloud.
- Swedish Special Forces SPIES and Military SMS Safety lessons from a serious incident during a Swedish Special Forces trial of Special Patrol Insertion and Extraction System (SPIES) under a UH-60M helicopter.
- Swedish NH90 CFIT: Pilot Experience and Skating on Frozen Lake A Swedish NH90 crew with low experience on type had a lucky escape when they inadvertently descended and struck a frozen lake during an exercise in Norway.
- Korean T-50 Accident at Singapore Airshow During the take off of a military jet trainer nose wheel steering was disengaged when the nose wheel was not aligned with the direction of travel. The aircraft zig-zagged for 750m before going off the runway and over turning.
- HF Lessons from an AS365N3+ Gear Up Landing
- Easyjet A319 Heavy Landing
- A320 Flown on After Damaging Heavy Landing
- G200 Leaves Runway in Abuja Due to “Improper” Handling
- UPDATE 19 July 2019: Twin Otter Nose Wheel Steering Misused in Runway Excursion
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