In 1978 Sri Lanka was emerging from a long period of economic isolation. A landmark election the year before had ushered in a change of government, with a mandate to open up the economy. Rebuilding ties with the West, long-ignored during a period of austerity and socialist policies, was a priority for the new regime.
Four years earlier, on 4 December, 1974, the tragic crash of Martinair 138, a chartered McDonnell Douglas DC-8-55CF (see Daily FT, Sri Lanka’s worst air disaster), had shocked the entire world, as it was the worst aviation disaster (by death toll) at the time.
That aircraft, operating a Hajj pilgrimage charter en route from Surabaya, Indonesia to Jeddah, Saudia Arabia, had impacted the ‘Seven Virgins’ mountains in Sri Lanka’s Maskeliya region while on descent to Colombo’s Katunayake Airport (CMB/CAK) at night. The probable causes of the accident included a lack of radar equipment and other infrastructure shortcomings at the airport.
By 1978 much had been done to address those issues. A radar system had been procured and installed at Katunayake. The aeronautical navigation equipment had also been upgraded; a VOR (Very High Frequency Omni-Directional range) beacon had been made operational, and DME (Distance Measuring Equipment) added to it; an Instrument Landing System (ILS) supplemented by a VASI (Visual Approach Slope Indicator) were installed on Katunayake’s Runway 22 (aligned along the compass heading of 220 degrees), with its approach end over land to the northeast of the airport.
But there were still serious deficiencies. The associated approach lighting system (ALS), which assists pilots in seeing the runway, was not working, and the DME equipment was unserviceable on that fateful night in 1978.
The scene is set
Loftleidir Icelandic Airlines Flight 001 was approaching Colombo from Jeddah, Saudi Arabia, en route to Surabaya, Indonesia on November 15, 1978. Ironically, this was in the reverse, or ‘mirror-image’, circumstances to the ill-fated Martinair DC-8. This was a chartered Icelandic DC-8-63CF also carrying a load of Indonesian Muslim pilgrims returning home from their sacred pilgrimage.
The Loftleidir pilots and cabin crew were probably looking forward to a relaxing layover in Colombo, as another team of colleagues were waiting to take the aircraft on its next leg. The flight had departed Jeddah at 15:58 local time (17:28 Sri Lanka time) and flown through the evening, first contacting Colombo Air Traffic Control at 22:53 local time.
The ‘duty runway’ at Katunayake was ‘04’, probably due to the prevailing North East monsoonal winds that night. (It should be noted that Runway 04 occupies the same ‘physical’ runway or ‘piece of concrete’ as ‘22’, but aligned toward the diametrically opposite compass heading of 40°, or ‘040’, degrees for approaches from the south west). However, ‘04’ did not have an ILS, and because most of the approach was over the sea and, finally, the Negombo lagoon, a pronounced ‘black hole’ effect was a concern.
The crew requested, and were approved, to instead conduct an approach and landing on Runway 22, from the opposite direction. This runway did have an ILS approach, although the ALS was unserviceable – a fact the crew must have been aware of as it was published in the Notices to Airmen (NOTAM) issued by the airport.
Instrument Landing Systems
An ILS approach provides two radio beams, one of which, the ‘localizer’, guides the aircraft on a straight line aligned with the runway centreline from about 12 miles out. At a particular spot on that track the aircraft will intercept the ‘glideslope’, the second radio signal that provides a gentle 3-degree slope to a point on the runway, a minimum altitude known as the MDA, that will provide clearance from obstacles on the ground during the final approach.
A Category 1 ILS approach, the type that was installed at CAK, brings the aircraft down to an altitude of about 200 ft above the runway (the MDA). At this stage the pilots must see the runway ‘environment’ (which the approach lights would help identify – except they were not working that night) before transitioning from flying by reference to their instruments to a visual landing while actually looking at the runway.
It is imperative that the aircraft must not proceed below the MDA unless the runway environment is in sight. In the case of CAK’s Runway 22, the MDA was 228 ft above mean sea level (AMSL). The crew would ‘bug’, or mark, this altitude on both the barometric altimeter (which senses atmospheric pressure) and the radio altimeter; the latter measures distance to the ground immediately below the aircraft.
As the aircraft descends on the ILS, the Pilot Monitoring (PM) will call “one hundred above” (the MDA), a warning to the Pilot Flying (PF) that the ground is very close. At the MDA the PM will call “minimums”, at which stage the PF will respond “Landing”, which means the runway environment is in sight; or else “Go Around” — which is followed by the addition of engine thrust and an increase in pitch attitude enabling the aircraft to climb away from the approaching ground.
Properly flown, an ILS will describe a smooth line showing a gradual descent to the runway. However, should the pilots not ‘establish’ the aircraft on a stable track, they will tend to alternately overshoot and undershoot the two radio beams, making for what is known as an ‘unstabilised’ approach.
Initially a normal approach
‘Lima Lima 001’ (to use the radio call sign designated to the Loftleidir flight) was cleared for the ILS approach by the radar controller at 23:06 local time and was asked to “report established on the localiser” – the lateral guidance beam of the ILS. But the DC-8’s crew failed to acknowledge or comply with the instruction, so the air traffic controller kept giving them helpful (to his way of thinking) advisory information on their track and altitude. The last such transmission was at 23:27:26 when the controller said “Lima Lima 001, slightly to the left of (runway) centreline, very slightly to the left of centreline, two miles from touchdown, height 650 feet, cleared to land-off this approach.” The only response received was “Roger”, the accepted term for ‘understood’ in radio parlance.
While possibly helpful, the radar controller’s comments were non-standard. The pilots are responsible for navigation, and would have been concentrating hard on their instruments to follow the prescribed flight path. A Douglas DC-8, never an easy aircraft to fly, is equipped with small ‘dial’ or analogue gauges, not the large flat-panel LCD screens seen on modern airliners.
The Captain, who was the PF, would have been scanning a number of instruments (most of them smaller in diameter than a teacup) to control the aircraft’s speed, descent rate and lateral track. The co-pilot, who was handling the radio, would have been the monitoring pilot (PM), tasked with communications, and configuring the flaps and landing gear while keeping an eye on the instruments too. Compounding matters, the approach was at night, to an unfamiliar airfield, with thunderstorms in the vicinity — a challenging scenario at the best of times.
Lack of stabilisation
One aspect that stands out from the subsequent accident report, which was produced by a Presidential Commission of Inquiry appointed by the Sri Lankan Government, is that flight LL001 never really flew a stable descent on the ILS.
The flight data recorder and the cockpit voice recorder (the so called ‘black boxes’ which are actually painted orange) were both recovered, and show that the DC-8 was not stable on the ILS but ‘chasing’ the beams, never maintaining a constant heading or rate of descent. This is what probably caused the radar controller to provide what he thought were helpful comments on the radio.
Less than a minute after the last radio transmission from the air traffic controller, Icelandic 001 crashed a mile short of the runway, impacting coconut trees that stood 163 ft above the runway altitude.
Accident and the aftermath
The accident occurred late at night in an area that was at the time largely uninhabited. The initial impact had been with the tall trees on a coconut plantation, and then the aircraft proceeded to hit rubber trees on the adjoining estate. The fuselage and wings broke into sections that were scattered in the vicinity. Fire engulfed the area and 175 passengers, plus eight crewmembers (including both the pilots) were killed.
Rescue teams from both the airport and nearby Sri Lanka Air Force base rushed to the scene. Five of the crew and 74 passengers were rescued and moved to nearby hospitals.
At the time it occurred, the Loftleidir Icelandic crash was one of the worst accidents in the world, with a death toll only slightly less than that of the Martinair crash near Maskeliya in 1974. It made headlines all over the world and thrust Sri Lanka’s safety record into a harsh global spotlight.
(The report of the Presidential Commission appointed to investigate the accident and an analysis of the outcomes will be the subject of future column)