Accidents and incidents involving the JAS 39 Gripen

From Wikipedia, the free encyclopedia
Jump to: navigation, search
The Gripen at Farnborough Airshow 2006.

The JAS 39 Gripen is a fighter aircraft manufactured by the Swedish aerospace company Saab.

As of May 2010, five Gripens were destroyed in crashes, two of them before the delivery to the Swedish Air Force. These aircraft included one prototype, one production aircraft and three in service with the Swedish Air Force. In addition, one aircraft was lost in a ground accident during an engine test, for a total of six hull losses. No lives have yet been lost in accidents with the Gripen. Gripens have also been involved in several aviation incidents.

Crashes during testing[edit]

A sculpture in stainless steel by Thomas Qvarsebo, depicting a paper plane with a crumpled nose, has been placed on the spot of the 1993 crash.

February 1989[edit]

On 2 February 1989, the first prototype JAS 39-1 crashed on its sixth flight, when attempting to land in Linköping. The accident was filmed in a now famous recording by a crew from Sveriges Television's Aktuellt.[1] The pilot, Lars Rådeström, remained in the tumbling aircraft, and escaped with a fractured elbow and some minor injuries. The crash was the result of pilot-induced oscillation (PIO). Extremely gusty winds were also a contributing factor.[2]

August 1993[edit]

On 8 August 1993, a production JAS 39A Gripen (serial number 39-102[2]) crashed on the central Stockholm island of Långholmen, near the Västerbron bridge, when the aircraft stalled after a slow speed manoeuver during a display over the Stockholm Water Festival. The crash was, like the first one, caused by pilot-induced oscillation, and caught on film.[3] The pilot – Rådeström again – ejected from the aircraft, and landed safely by parachute, though he became stuck in a tree. The aircraft fell to the ground and caught fire on impact. Despite large crowds of onlookers, only one person on the ground was injured,[a] and the fire was soon put out.

The aircraft had been delivered to the Swedish Defence Materiel Administration in June, only two months prior to the crash.[2] The display flight was not classified as in-service, because it was being flown at a display by a test pilot, rather than a Swedish Air Force officer.

Crashes in service[edit]

The only in-service crashes so far have involved the Swedish Air Force.

Swedish Air Force[edit]

September 1999[edit]

On 20 September 1999, a JAS 39A Gripen (serial no 39-156[2]) from Airwing F 7 Såtenäs crashed into Lake Vänern during a dogfight exercise. After passing through the wake vortex of the other aircraft, the aircraft abruptly changed course, and the pilot, Capt. Rickard Mattsson,[2] got a highest-severity warning from the ground-collision warning system. He ejected from the aircraft, and landed safely by parachute in the lake, where his colleague observed him getting into the inflatable life raft. He was picked up by a rescue helicopter 27 minutes later.

The Swedish Accident Investigation Board (SHK) could not fully determine the cause of the crash until the black box was found some 15 months later. The preliminary report is available in English.[5]

SHK's final report – not available in English – concluded that the plane had passed through the other aircraft's wake vortex while in a steep (−70 degrees) dive. When passing, the pilot's pitch command was "up", but instead the vortex inflicted a large aerodynamic transient on the aircraft, throwing it down into an almost vertical (−85 degrees) dive. These factors combined to create an angle of attack that was too large for the command to be obeyed, and so the ground-collision warning system alerted the pilot that a turn to avoid a crash would require more than 10 g. The pilot elected to vacate the aircraft in accordance with the flight manual. At the same moment the vortex effect ceased, reducing the angle of attack to within flyable limits. Although the aircraft could theoretically have been saved, the ejection sequence had already been initiated and could not be stopped.

The flight status at the moment of ejection was: altitude 750 m, flight angle −75 degrees, speed 350 km/h, angle of attack −8 degrees, and load −1.5 g.[6]

June 2005[edit]

On 1 June 2005, a JAS 39A Gripen (serial no 39-184) from Airwing F 17 Kallinge, when acting as a target in a dogfight exercise, apparently ceased to obey commands from the pilot, LtCol Axel Nilsson. After attempting to regain control while the aircraft slowly descended, the pilot ejected from the aircraft and landed safely by parachute.

SHK's investigation – report published in June 2007 – showed that the aircraft initially travelled at Mach 0.6 in a shallow dive at an altitude of 5500 m. When attacked, the pilot, not fully aware of the rather low speed, tried to escape by taking the plane into a steep (60 degrees) climb. This led to a "low speed"-warning, for which the pilot tried to compensate by lighting the afterburner and manoeuvering into an offset looping, briefly applying maximum angle of attack. The intent was to regain speed at the top of the loop. However, the speed was too low, and the aircraft ended up in an inverted (upside-down) superstall, and started to descend slowly.

While there are measures to get out of this situation, those taken by the not-fully-trained pilot were either inadequate, insufficient or counter-productive, and he ultimately had to abandon the aircraft.[7]

April 2007[edit]

On 19 April 2007, a JAS 39C Gripen (serial no 39-259) from Airwing F 21 Luleå crashed at the Vidsel airfield in northern Sweden.[8] The pilot, Capt. Stefan Kaarle, was involuntarily ejected out of the aircraft in mid-air while approaching the airstrip in order to land. He landed safely by parachute. All C/D Gripens were temporarily grounded. The ejection seat handle – placed between the pilot's thighs – had been activated by the motions of the pilot's flight suit. Repeated jerks on the handle, resulting from the G-suit inflating and deflating during the flight, had ultimately exerted enough force on it to cause the ejection. Moments before the ejection, the pilot had taken the aircraft into a tight turn, thus causing the G-suit to activate.

For the C and D models of Gripen, the ejection seat handle had been moved and redesigned to make room for larger cockpit displays. The investigation showed that the new handle was prone to these kinds of uncommanded ejections. A survey among the air-wings that fly the Gripen revealed that the ejection handle had become dislodged before, though not far enough to cause an ejection. The investigation concluded that the quality assurance procedures between the Swedish Defense Material Administration, the Swedish Air Force and Saab were not adequate to discover the error in time and were therefore cited as the root cause of the accident.[9]

Other incidents[edit]

Swedish Air Force[edit]

October 2007[edit]

On 3 October 2007, a Swedish Air Force Gripen had a separation conflict with a passenger aircraft, i.e. they did not keep the required separation in altitude and distance. The passenger aircraft was a Saab 340 from Avitrans Nordic on its way from Ronneby to Bromma. At their closest, the aircraft were separated 30 meters vertically and 950 meters horizontally. The incident took place in the airspace south of Oskarshamn. The pilot on the passenger aircraft was alerted by the TCAS that another aircraft was approaching at the same altitude.[citation needed]

SHK concluded that the incident took place because the Gripen pilot inadvertently went below his assigned flight level and ended up on the same flight level at the passenger aircraft. SHK placed the root cause of this with the lack of adequate routines in the Swedish Air Force for receiving and reading back instructions from air traffic control. A contributary cause of the incident was said to be a lack of support systems in the Gripen to help the pilot with the aforementioned task. Such a system is currently being introduced in the Swedish Air Force Gripens. The system will alert the pilot if the flight deviates from the assigned flight level.[10]

August 2009[edit]

On 6 August 2009, a Gripen from F 17 Kallinge belly-landed after a routine mission and skidded off the runway. A minor fire broke out, but it was soon put out by the airbase fire brigade. The cause is believed to be pilot error. A witness observing the plane landing claimed the nosewheel collapsed on the runway but this claim is unlikely. What he saw from such a long distance was more likely the front landing light lamp, which on the Gripen is placed in the hatch to the front landing gear and not on the landing gear itself where it would only be visible when the gear is out, in combination with the collapsing external fuel tank under the plane. The pilot escaped unharmed and could walk away from the aircraft. SHK will investigate the incident.[11][12]

May 2010[edit]

On 31 May 2010, a Gripen from F 21 Luleå came loose and speeded away during a static engine test. The aircraft gained considerable speed before rolling off the hard surface and onto nearby soft terrain, where it finally flipped over.[13][14] The technician in the aircraft, lieutenant Sandra Halvarsson, escaped with minor injuries.[15] There is unconfirmed information that the engine was accidentally started with full throttle.[16] As the accident did not involve a plane flying or preparing to fly, it is not considered to be a crash.

Czech Air Force[edit]

October 2006[edit]

On 11 October 2006, a pilot from the Czech Air Force flying a Gripen almost hit a target-towing Learjet 35 in a live fire exercise at Vidsel airfield in northern Sweden. When practicing using the on-board automatic cannon, the Czech pilots mistakenly targeted a reserve target close to the towing plane instead of the intended target 600 meters behind it. After several "dry runs", live firing commenced, and the first pilot fired on the reserve target. Several rounds hit it, and were calculated to have passed within 10 meters of the Learjet. After this the Czech pilots discovered the actual target they were supposed to fire on, and proceeded to attack it instead. The crew of the Learjet did not notice anything out of the ordinary besides hearing the sound of the cannon, without making the connection that they had been fired upon. The incident was discovered after landing.

SHK's investigation concluded that the causes of the incident were that too many activities were scheduled for too short a time span; that the safety regulations concerning live fire exercises were outdated; and that the assignment of responsibilities and duties of the Swedish Armed Forces, the Swedish Defence Material Administration, Saab Special Flight Operations and the Czech military units were unclear. These causes put together resulted in the Czech pilots not being fully aware of the true configuration of the Learjet and the targets, which in turn led to them targeting the wrong target and one of them eventually firing on it. Contributing causes were that the Czech pilots had little to no experience of this kind of exercise, and that the target-towing Learjet had no means of monitoring the exercise. For instance the Learjet lacked a radar warning receiver that could have revealed that they had been targeted by the Gripens.[17]

Notes[edit]

  1. ^ A woman was hospitalized for three weeks for burns.[4]

References[edit]

  1. ^ Sveriges Television (You tube) (in Swedish), Google .
  2. ^ a b c d e Lindqvist, Gunnar & Widfeldt, Bo, Rikets flygplanköp – JAS 39 Gripen, Nässjö, SE: Air Historic Research, 2003, ISBN 91-973892-5-0, pp. 164–68 (Swedish).
  3. ^ Sveriges Television (You tube) (in Swedish), Google .
  4. ^ Coping with a Credibility Crisis: The Stockholm JAS Fighter Crash of 1993 (PDF), Swedish National Defence College, p. 27, retrieved 23 January 2012 .
  5. ^ Statens haverikommission, SHK (Swedish Accident Investigation Board).
  6. ^ "Rapport RM 2002:02", Swedish Accident Investigation Board (Swedish).
  7. ^ "Rapport RM 2007:03", Swedish Accident Investigation Board (Swedish).
  8. ^ "Jas aircraft crashed in Norrbotten", Sveriges Television (Swedish).
  9. ^ "Rapport RM 2008:01", Swedish Accident Investigation Board (Swedish).
  10. ^ "Rapport RM 2010:01", Swedish Accident Investigation Board (Swedish).
  11. ^ "Jas-plan buklandade i Blekinge" (Jas aircraft belly-landed in Blekinge), Göteborgs-Posten, 6 August 2009 (Swedish).
  12. ^ "Vittne såg noshjulet vika sig" (Witness saw the nosewheel collapse), Ny Teknik, 7 August 2009 (Swedish).
  13. ^ "Jas-plan voltade på F 21 i Luleå" (Jas aircraft flipped over at F21 in Luleå), Göteborgs-Posten, 31 May 2010 (Swedish).
  14. ^ "Haveri med JAS 39 Gripenflygplan" (Incident with JAS 39 Gripen aircraft), press statement from F 21 Luleå, 31 May 2010 (Swedish).
  15. ^ ”Jag hade änglavakt” (”I had a guardian angel”), interview released by F 21 Luleå, 2 June 2010 (Swedish).
  16. ^ "Frågetecken kring skenande Jas-plan" (Swedish). Sveriges Television, 1 June 2010. (English translation).
  17. ^ Rapport RM (PDF) (in Swedish) (4), Swedish Accident Investigation Board, 2007 .

External links[edit]