|Date||August 9, 1978|
|Summary||Engine explosion at takeoff, resulting in loss of thrust|
|Aircraft type||Boeing 747-284B|
|Aircraft name||Olympic Zeus|
|Flight origin||Ellinikon International Airport|
|Destination||John F. Kennedy International Airport|
Olympic Airways Flight 411, from Ellinikon International Airport bound for John F. Kennedy International Airport operated using a Boeing 747-200 on August 9, 1978 came close to crashing in downtown Athens following an engine explosion while taking off. Despite maneuvers near the edge of the flight envelope, none of the 418 passengers or crew suffered serious injury.
The Boeing 747 was the first "jumbo jet". It was a prestige aircraft in the 1970's and purchased by many airlines as a fleet flagship. Olympic Airways was the flag carrier for Greece and had purchased 747's for some of its prime routes, including a non-stop between Athens and New York. It received its first 747, registered as SX-OAA in June, 1973. The large passenger capacity meant lower per-seat costs to the airlines that operated it. For Olympic, this meant that large numbers of American tourists could be accommodated. Ellinikon in the Athens suburb of Elliniko was the international airport for the capital city and the primary entry and departure point for Americans visiting Greece.
The Captain of the incident flight, Sifis Migadis, had 32 years of experience with Olympic The First Officer Kostas Fikardos was also considered experienced and was a close friend of Migadis.
SX-OAA, named "Olympic Zeus" was the first -200 series 747 that Olympic purchased and fitted in a two-class configuration with executive class seating on the upper deck and nose section of the lower deck and economy class for the remainder of the lower deck.
Just before 14:00, the fully loaded airplane including 138-150 tons of jet fuel, began its take-off run on the Hellenikon runway with either 374 or 418 or 431 passengers (conflicting sources) on board (mostly American tourists returning home after their summer vacations in Greece) including 20 crew. The moment the aircraft reached VR (rotation speed, i.e., the speed that allows the captain to raise the plane's nose, following V1, i.e., the speed after which the take-off cannot be aborted) the crew heard a loud blast. Engine #3 had exploded but at the time the captain had doubts if that was an engine explosion or a tire blow-up. Strapped in her seat at the front of the passengers' cabin, air-hostess Lucia Siachou received an intercom call from a colleague at the back who had a better view on the blown-up engine saying "we are screwed" to which she replied "I know". The explosion was also witnessed by the control-tower personnel that gathered to watch in horror as the crippled plane was trying to gain altitude. Debris and mechanical components from the disintegrating engine were spreading across the runway and on the nearby rooftops.
In the meantime, two elements jeopardised further flight 411: a) due to a recent overhaul, engine #2 could not deliver more than 96% of its maximum thrust instead of the expected 110% and b) when the captain ordered the flight engineer to switch-on the alcohol enrichment valve (in the 1970s, alcohol fuel-enrichment systems were installed on airliners to enhance performance), he accidentally switched it off thus depriving the remaining three engines of the necessary extra power needed to lift the fully-loaded behemoth. Both elements were crucial in the events that unfolded.
The moment he became airborne, immediately after the blast, Captain Migadis - a veteran combat pilot and three-decades aviator - issued the order "gear, up" to his first officer and life-long friend, veteran aviator Fikardos; the latter complied, against recommendations on Boeing manuals and checklists. The plane's constructor argued that, in case of a power loss, the retraction of the undercarriage - a 15-second procedure that included the opening and closing of the gear bay doors - would provide extra drag and therefore further compromising the plane's fragile air-speed. Captain Migadis, on the other hand, overrode the official procedure arguing that he had to preserve as much air speed as possible on the long term, because he had to clear a 200ft (~65m) hill 1.5km (~0.9miles) ahead. It was a gamble, as he immediately jeopardised the ability of the already struggling airliner to climb.
Indeed, astonished tower-control personnel and bystanders were watching in horror the heavy aircraft that could not gain altitude, flying just above the runway and barely clearing the perimeter's 4-meter-high (12ft) fence, at the airport's west end. When the landing gear retracted fully and the bay doors closed, the plane managed to gain some air-speed and height; the pilot's gamble had paid off. However, the 200ft (~65m) Pani/Panós hill (in English: Pan's hill) less than a mile a head, in Alimos district, forced Migadis to pitch-up the nose and steeply climb; therefore further reducing his already low air-speed. The flight data recorder showed that he barely cleared the hill by a 9ft (~3m) margin at a 209ft altitude. This mandatory maneuver drained away more power and air speed, and so the airplane almost stalled.
People on the control tower breathed a sigh of relief when the aircraft disappeared behind the far side of Pan's hill without being replaced by a huge fireball. But they knew the airliner could not have gone far. A young pilot rushed to the office of Olympic Airways' Aviation Safety Director, capt. Tsolakes, urging him: "Sir, come and see an airliner that is going to fall into the sea!".
Migadis, after clearing Pan's hill, saw his air-speed dropping below the nominal stalling point of that day's configuration (172 knots) and way below the minimum speed of safe level flight (180 knots). The captain tried, at that point, intentionally to trade altitude for speed pitching down; his goal was to sacrifice about 50 ft (15m) of the distance between him and the ground, for 5 to 6 knots of air speed. But after descending to just above the buildings below him, at a sea-level height of (according to the flight data recorder) 157ft (~55m), he was forced to level the damaged aircraft, leaving himself practically without any altitude and options.
The plane's belly was barely clearing the television antennas on the rooftops beneath, at the districts of Kallithea and New Smyrna. The captain saw his tachymeter registering speeds of 164 knots, much below the calculated stalling point (the flight data recorder later showed even lower speeds; 160 and 158 knots for that segment of the flight). People on the ground looked up in disbelief to see the gigantic airplane flying so close to them. Air-hostess Siachou could clearly see the clotheslines stretched on the roofs of 6 or 8-storey buildings and shocked housewives drying their laundry as they were watching in terror the plane passing just a few meters overhead. Moments later, the aircraft flew next to the highest floor of the 14-storey-tall Interamerican Tower and the air-stewardess could distinguish the facial expressions of the stunned staff and employees that were staring at the flying behemoth passing them. The plane was flying so low that when it crossed Syggrou Avenue, a 10-lane highway under contraction at that time, it raised a thick cloud of dust.
At this point, Migadis considered everyone on board dead; he was trying to find a clear spot to crash-land his crippled aircraft without substantial loss of life on the ground. The Aegaleo mountain ridge (400-500m high at some points/~1200-1600ft) far ahead and the Panionios' Football Stadium (New Smyrna district's A-league football club) where the two most viable proposals. Air-hostess Siachou was thinking about her two children (a 6-year-old son and a 2-year-old daughter) and their fate as motherless orphans. She consoled herself thinking that at least they would get a large amount of money from the company and the Greek government in case she died; after those thoughts run through her head, she reached a calm emotional state beyond fear. Second-officer Tribos, in the cockpit, realized that his body was stiff from the adrenaline rush and told himself "Relax and die like a man!".
Nevertheless, the entire crew maintained their resolve and superficial calmness to such an extent that most of the passengers believed this was an intended farewell site-seeing tour and some of them also took some photos.
Athens is a 3.5-million densely populated metropolis, built on flat terrain. The capital of Greece has a triangular shape; its base is formed by the seafront while its vertex is pointing north-east. The city is completely surrounded by mountains 900-1100m high (3000-3500ft) except its western side. There, a relatively low (300-500m high/~1000-1600ft) mountain ridge exists, named Aegaleo mountain. From the Hellenikon airport (on the east end of the city) to Aegaleo mountain (at the western limit of the Greek capital) the distance is about 12km (~7miles) on a straight line. After more than a minute struggling to remain airborne over the dense urban area, captain Migadis thought that he would inevitably fell upon the low mountain that nevertheless could not overfly.
At that point, the captain himself deduced that he had maintained the plane airborne, despite the below-stall-point air speed, due to: a) his earlier-than-usual retraction of the landing gear; b) his successful efforts to maintain the huge airplane in a completely horizontal position (planes lose part of their lift while banking or pitching) and c) the ground effect. The extremely hot weather of a typical Greek mid-summer day added further difficulties to the struggling aircraft. Hot air is thinner and provides lesser lift. Above the ultra-dense urban area of the capital, that day, the temperature was higher than 43°C (108°F). People watching from the ground saw the huge belly of the plane passing over.
A few moments later, the plane exited the dense urban area and entered the sparse vegetation and rocky terrain on the foot of Mt. Aigaleo. Migadis, knowing that he could not clear the imposing ridge in front of him, was searching for the best site to crash land. But, then, three factors changed his fortune again.
First, the flight engineer managed, at last, to optimize the three remaining engines' performance. Sources do not specify if that included, among other measures, the opening of the alcohol-enrichment valves previously closed by accident. Second, a usual and well-known south-west sea-breeze begun to blow against the aircraft's nose and left wing, adding further to the crippled planes's air-speed. Third, the air temperature outside the city was around 38°C (100°F) and this colder air provided more lift.
Ninety-two seconds into the flight, the plane begun to rise after the tachymeter-needle had steadily passed the 170 and 180 knots mark. But there was a catch: their risinthe altimeter was measuring sea-level altitude instead of actual altitude; the ground below them was rising faster than the heavy aircraft could climb because of the ascending mountain slope. But Migadis did not intend to leave matters unfold by themselves: still he could not clear the Aigaleo ridge by overflying it; but he realized that he had enough air-speed and power to bank and thus avoid it. He eventually turned the plane southwards, towards the sea-front and away from any land features. He even felt confident enough to retract the flaps at 300ft. Once above the sea, he dropped most of the fuel (calculated to last from Athens to New York) and the crippled aircraft managed to gain further altitude up to 1500ft, which made it possible for Migadis to make a gradual turn. The aircraft returned to Ellinikon International Airport safely. Migadis flew another airliner to New York that same evening.
The plane's water injection system had been left on prior to take-off, and the flight engineer failed to notice this during pre-flight checks, flipping the switch to the 'off' position. Without water injection to cool off the engines, engine number three exploded.