Olympic Airways Flight 411

The Boeing 747 was the first "jumbo jet". It was a prestige aircraft in the 1970s and purchased by many airlines as a fleet flagship.[1] Olympic Airways was the flag carrier for Greece and had purchased 747s for some of its prime routes, including a non-stop between Athens and New York.[2] It received its first 747, registered as SX-OAA in June, 1973.[3] The large passenger capacity meant lower per-seat costs to the airlines that operated it.[1] For Olympic, this meant that large numbers of American tourists could be accommodated.[2] 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[4] The first officer Kostas Fikardos was also considered experienced and was a close friend of Migadis.[5]

An Olympic Airways 747-200 similar to the one involved in the incident showing the aircraft livery in use at the time.

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.[6]

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.[2] Engine #3 had exploded but at the time the captain had doubts if that was an engine explosion or a tire blow-up.[7] 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"[8] to which she replied "I know". The explosion was also witnessed by the control-tower personnel that gathered to watch in horror as the 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 747. Both elements were crucial in the events that unfolded.

The moment he became airborne, immediately after the blast, Captain Migadis—a veteran combat pilot who had been flying for three decades—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 thus would decrease the plane's acceleration. Captain Migadis overrode the official procedure, arguing that he had to preserve as much airspeed as possible in the long term, because he had to clear a 200 ft (approx. 65 m) hill 1.5 km (about 0.9 miles) ahead. It was a gamble, as he jeopardised, in the short term, the ability of the 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 (12 ft) fence at the airport's west end. When the landing gear retracted fully and the bay doors closed, the plane managed to gain some airspeed and altitude; the pilot's gamble had paid off. However, the 200 ft (approx. 65 m) Pani/Panós hill (in English: Pan's hill) less than a mile ahead, in Alimos[2] district, forced Migadis to pitch up and climb steeply, thereby reducing his already low airspeed. The flight data recorder showed that he barely cleared the hill by 9 ft (3 m) at 209 ft MSL. This mandatory maneuver bled airspeed, so the airplane almost stalled.

People in 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!"[9].

Migadis, after clearing Pan's hill, saw his airspeed drop below the nominal stall speed[10] for the plane's configuration (172 knots) and far below the minimum safe speed in level flight (180 knots). The captain tried, at that point, to trade altitude for speed by pitching down; his goal was to sacrifice about 50 ft (15 m) of altitude for 5 to 6 knots of airspeed. He descended to an altitude of 157 ft (55 m) MSL (according to the flight data recorder), barely above the buildings below him.

The plane's belly was barely clearing the television antennas on the rooftops[5] in the districts of Kallithea and New Smyrna. The airspeed indicator showed 164 knots, far below the calculated stall speed (the flight data recorder later showed even lower speeds—160 knots 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.[4] 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 hostess 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 construction at that time, it raised a thick cloud of dust.[11]

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 to 500 m (1200 to 1600 ft) high at some points—far ahead and the Panionios' Football Stadium (New Smyrna district's A-league football club) were 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 ran 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!".[12]

Nevertheless, the entire crew maintained their resolve and outwardly calmness to such an extent that most of the passengers believed this was an intended farewell sightseeing tour and some of them even took photos.

Athens was a densely populated metropolis with 3.5 million people, built on flat terrain. The capital of Greece has a triangular shape; its base is formed by the seafront while its vertex points northeast. The city is completely surrounded by mountains 900 to 1100 m (3000 to 3500 ft) high except its western side. There, a relatively low (300 to 500 m or 1000 1600 ft) 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 12 km (7 mi) 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 fall upon the low mountain that he could not overfly.

At that point, the captain himself realized that he had kept the plane airborne—despite the below-stall-point airspeed, because of (a) his earlier-than-usual retraction of the landing gear; (b) his successful efforts to maintain the huge airplane straight and level (planes lose 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 less lift. Above the ultra-dense urban area of the capital that day, the temperature was greater than 43 °C (108 °F). People watching from the ground saw the huge belly of the plane passing overhead.[4]

A few moments later, the plane exited the dense urban area and entered the sparse vegetation and rocky terrain at 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 began to blow against the aircraft's nose and left wing, adding further to the crippled plane's airspeed. 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 began to rise after the tachymeter-needle had steadily passed the 170 and 180 knots mark. But there was a catch: their rise in the 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 let matters unfold by themselves. Still he could not clear the Aigaleo ridge by overflying it but he realized that he had enough airspeed 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.[13] The aircraft returned to Ellinikon International Airport safely. Migadis flew another airliner to New York that same evening.