Garuda Flight GA-200 Crashes
Yogyakarta Airport Accident in Indonesia Raises Questions
Garuda flight GA-200, a Boeing 737-497 (PK-GZC), crashed on landing from Jakarta to Yogyakarta March 7, 2007. Here's what the investigation will focus on?
Accident investigators unravel the events leading up to an airline tragedy by gathering all the data from the Digital Flight Data Recorder (DFDR), the Cockpit Voice Recorder (CVR), the National Weather Service (NWS), the Terminal Radar Approach Control (TRACON) and the Terminal or Airport Control facilities. They will also put a team together made up of engineers from the manufacturer of the aircraft (Boeing), the engine manufacturer (CFM), maintenance specialists, pilot groups, weather specialists and human factors personal. Once all the technical, audio and video data is collected the results will be calculated. It will be the same for this accident on March 7th 2007.
The airport at Yogyaharta, Adisutjipto International Airport (WIIJ-ICAO or JOG-IATA) is what is called a category 1b airport. It has an ICAO Category 6 rating, which puts it just about in the middle of airline capabilities. Based upon this rating the largest possible aircraft that is allowed to land there is the Boeing B-737-400 (or competing type aircraft series.)
Garuda flight GA-200 was a Boeing 737-497 (PK-GZC) on a flight from Jakarta to Yogyakarta – a distance of about 455 km (285 miles). A Boeing will not climb to max altitude on a flight of this distance but climb to an intermediate altitude between 22,000 and 28,000 feet. The plane attempted to land on runway 9. There is another small grass runway used for glider aircraft parallel to runway 9 called 9R. GA-200 overshot the runway and stopped outside the airport movement area.
The weather from 5 stations reported visibility ranges from 5km to 29km. The runway was cracked in May 2006 from a powerful earthquake; however, it had been repaired but reported by pilots to “have a big bump.”
The maximum landing weight of the -400 is 124,000 lbs or 56,200 Kg. At 55,000 kg the Vref (approach speed) for flaps 40 landing is 137 kts and 130 kts at 50,000 kg. Fuel burn is 2,400 kg per hour at long range cruise.
The pilot would use Flaps 30 or 40 on this runway along with Vref+5 kts. We do not know whether there were any MEL items aboard (items that do not work on the aircraft) Governing agencies and the manufacturers say these may not be necessary if landing distance etc is taken into account; however, we will assume there are none.
The weight of the aircraft with the passengers and fuel (even if tankering fuel) would not be above 55,000kg. The weather was dry; the winds were light and no factor for landing. The aircraft was probably not at max landing weight based upon the length of the flight. The pilot would set the auto brakes at level 2-3 minimum. There was no distress call to the airport since nothing was mentioned by the controllers and the response time after the accident by firefighters was long.
The runway at WIIJ is short by commercial airline standards at 7,199 feet (2199 meters) in length. The maximum landing distance based upon a weight of 55 tons, dry runway, flaps 30, spoilers available, maximum reversers available, auto-brakes available (with Vref+5 of 146 kts); the landing distance would be 1,503 meters (including 50 feet above the threshold.). This means the Garuda flight should have had a minimum 696 meters of additional runway available for landing.
For every 5 kts above Vref+5 the landing distance increases 86 meters using auto-brakes 2 and a landing in the touchdown zone. A float caused by high speed would cause an additional factor of 15% under normal conditions, causing an increase to 99 meters per 5 kts above Vref. In order to exit the runway, the aircraft would have to increase its speed by 37 kts above Vref+5 (not unheard of in cases of suspected windshear.) This would require a distance of 2,246 meters at a speed of 183 kts.
When all this data is examined a pattern will emerge. The public will probably learn that a profile of ground incursions (including over shoots) at Garuda Airlines exists; that may be a training problem, a CRM problem, or an experience problem.
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