On a routine morning in August 1983, the corps headquarters in Karachi received an unusual request from the Civil Aviation Authority (CAA). While landing at Karachi Airport runway 25R at 4:30 in the morning, Pan American Flight PA 073 had slid off the runway and sank into the mud. It was posing a hazard, all flight operations had been suspended and the CAA wanted the army to assist them in this crisis. Since wide-body aircraft were so new, Pakistan did not have a recovery kit for clearing the runway. The army is used to recovering heavy equipment when its gets bogged in soft terrain, but the ‘heaviest’ is usually a 40-ton tank.
A passenger aircraft was in a different league altogether but this was close to a national emergency since Karachi is the country’s largest and most important international airport.
PAN AM Boeing 747-121 'Belle of the Sea', Registration Number N738PA, which slid off the runway at Karachi Airport in August 1983. It was the fourteenth Jumbo to be built, and entered service in February 1970
Usually the Pakistan Army Corps of Electrical & Mechanical Engineers (EME) undertake recovery operations, but the armoured corps also recovers its tanks. Therefore, the corps headquarters rushed the commanding officer (CO) of its EME battalion and a CO of an armoured regiment located at Malir to the airport. A representative from an engineer battalion also reported at the site.
On arriving at the airport, they were somewhat intimidated by the sheer size of the Jumbo. The Boeing 747 was the largest aircraft in the aviation industry at that time, with an empty weight of 180 tons and takeoff weight exceeding 300 tons. The older 707s weighed half that.
Mr. Runatte, Head of the Atlantic Division at Pan American Airlines, presenting a shield to Col Mohiuddin
Pan Am was Boeing’s launch customer for the 747 and the Clipper Belle of the Sea (originally named as Clipper Defender), was amongst the first to be inducted in February 1970.
I found on the internet a very unusual photograph of this particular aircraft with five engine pods. My close friend Ejaz Haq who had captained a Jumbo in PIA as well as Emirates, and has tremendous knowledge of the history of the aviation industry, informed me that the fifth pod was a means of ferrying the huge Pratt and Whitney JT-9 engines. According to him, these engines were right at the forefront of the technology of the time and were prone to fail by their compressors stalling. They could only be repaired in the US but were too big to be carried by any freight aircraft of the time. They were therefore ferried by hanging them on an extra pylon. This was called fifth pod operation, pilots were specifically trained for this, and due to the drag, the entire performance envelope was downgraded. This was copied by McDonnel Douglas for the DC-10 with a fourth pod hung on the left wing between the left engine and the fuselage. Since PIA had both the 747 and the DC-10 its pilots were trained for both. That was the PIA of yesterday: always in the forefront and punching way above its weight. In any case, we return to our actual story.
PAN AM Flight PA073 was a late-night flight from Delhi. At 4:30 am most of the passengers were half-asleep as the cabin crews completed the cabin checks and the aircraft came into the finals.
It was raining and Capt. Ejaz Haq tells me that due to the rubber deposits on the runway in those days, Karachi runway 25R was notoriously slippery when wet, particularly the first 3,000 feet or so
It was raining and Capt. Ejaz Haq tells me that due to the rubber deposits on the runway in those days, Karachi runway 25R was notoriously slippery when wet, particularly the first 3,000 feet or so. A large aircraft has three systems to check its speed after it touches down. The pilot first applies the airbrakes which are large flaps on the wings that stand up vertically. Next they apply reverse thrust which deflects the engine thrust forward, further slowing the aircraft down. And finally there are the wheel brakes.
A summary of the accident report available on the internet states that on touch down, reverse thrust was applied on engines 1, 2 and 3. Engine 4, which had an unserviceable reverser, was left in forward idle.
When the aircraft slowed to 70 knots, the reverse power was decreased but suddenly the forward thrust on engine number 4 increased rapidly and the aircraft veered left. When the pilot applied the brakes and tried to steer the aircraft, it aquaplaned because of the heavy rain. Aquaplaning occurs when a layer of water builds between the wheels of the aircraft and the runway surface, leading to loss of traction and control inputs. The aircraft skidded off the runway sliding through soft rain-soaked soil before it came to rest.
The pulling operation of the PAN AM 747 in progress at Karachi Airport with an ARV M88 and M62 Wrecker Crane (August 1983)
As the plane stopped, Ms. Wynn one of the cabin crew who was seated at the rear felt rain and realized that the fuselage had cracked open. It was pitch dark in the cabin until the emergency lights came on after 15 seconds and the cabin crews started ushering the passengers to the emergency exits.
The evacuation of the aircraft had its hiccups. The first two doors that the crew tried to open were damaged. The third opened but the slide of the fourth was sucked into an engine which was still running and a couple of other exits also gave them trouble. However, owing to the efficiency of the cabin crew, the evacuation was completed in two minutes using just four exits. They found themselves standing in the mud and rain but none of the 243 passengers and 16 members of the crew sustained injuries.
The runway at Karachi Airport continued to be dangerous. Every second or third monsoon some large aircraft would not be able to stop on the runway and would overturn
When the aircraft skidded off the runway, the nose gear struck the concrete base of a Visual Approach Slope Indicator (VASI) and collapsed. The aircraft then slid on its nose 380 feet through soft mud before it came to rest with its tail 120 feet from the edge of the runway. Like a beached whale, most of the 232 feet length of the belly of the Jumbo was resting on the ground.
The army has learned the hard way how to carry out difficult recovery operations of tanks and other heavy equipment in the field.
The difference between trying and succeeding is the conviction that a task can be done. It is an attitude instilled in the Pakistan Army and yields results in both conflict scenarios as well as peacetime emergencies. To work well, this “Can Do” attitude requires professional competence, confidence, determination and teamwork – and these were adequately demonstrated in the crisis that occurred in 1983 at Karachi Airport.
However, this operation was more complex. The basic ingredients were similar to any such recovery operation, but the size of the aircraft complicated the whole situation. A plan was discussed and finalized. Time was of great essence and after analyzing the situation, all the required resources were mobilized.
PAN AM engineers and members of the Pakistan Army team after successfully recovering the Boeing 747 at Karachi Airport
A key element in executing the plan were two vehicles that represented the best of US military technology, the M88A1 (Hercules) Armoured Recovery Vehicle and the M62 Wrecker Crane. The M88 ARV, which had only recently been provided to the armoured regiments, was a 50-ton monster with a 280-feet winch that had a constant pull of 70 tons. This pull could be increased two to three times using pulleys to give a mechanical advantage. In addition, the M62 Wrecker had a winch with a capacity of 10 tons. The third piece of equipment was a 54 ton D9 Caterpillar Bulldozer to level the ground over which the aircraft was to be towed and the truck/trailer to transport it was also required for the recovery. In case additional pull was necessary, the D9 also had a winch of 20 tons’ capability.
While the equipment and personnel were being assembled, PAN AM dispatched their experts from Europe and Dubai to supervise the operation. Thinking ahead, the team had already ordered over 400 sheets of the thickest plywood in the market. A temporary track behind the wheels of the Jumbo was laid that extended back to the edge of the runway. All this had been completed by the evening by the time the PAN AM experts arrived, bringing with them large rubber bags. During the night, the rubber bags were inflated under the front section of the aircraft to enable the nose to be placed on the trailer of the transporter. The crews then took a much needed rest and waited for daylight. It was too delicate an operation to be attempted at night.
Fortunately, the main undercarriage was undamaged but it was resting in the mud. A rough calculation was carried out of the rolling resistance that had to be overcome and an elaborate ‘block and tackle’ arrangement was laid out and attached to the rear undercarriage. ‘Block and tackle’ is a term used for a combination of pulleys and cables that provide a mechanical advantage by multiplying the direct pull exerted by the towing winch(es). Then with the winch of the ARV attached to one assembly of the main undercarriage and that of the M62 to the other, the Jumbo was inched onto the plywood sheets. The tricky part was to ensure that the trailer supporting the nose section reversed at the same pace at which the aircraft was being pulled.
It was slow and steady work, foot by foot. But it was completed without a hitch in only 36 hours. For two years the Clipper Belle of the Sea remained parked on an apron. Because of the cracks in the fuselage, it was declared beyond economical repair and ultimately sold as junk.
The runway at Karachi Airport continued to be dangerous. Every second or third monsoon some large aircraft would not be able to stop on the runway and would overturn. Within a few years there were two such incidents with DC-10s of the PIA, as well as a Lufthansa and a KLM aircraft.
