The day when a Boeing 747 almost crashed on downtown Athens, SX-OAA, named Olympic Zeus,
The Captain Who Broke The Rules and saved 418 Lives (398 pax and 20 crew)
Olympic Airways 747 almost crash Athens 1974
Flying from ATH to JFK in August 1974 during the take off run on a typically hot Athens summers day the 747 was using water to assist the engines with extra thrust when a loud bang was heard but the Captain elected to continue the take off.
The aircraft just cleared the boundary fence and then against the Company rules Captain Migadis
elected to raise the gear.
He then traded some 50' of height for more speed.
He thought well, we were all dead, it's over. The aircraft was carrying 160 tons of fuel, as it would fly directly from Athens to New York.
In the main cabin Cabin Crew member Lucia Siachou got an intercom call from a colleague seated right at the back who had seen engine number three on the right hand side had blown up. The colleague said “we are screwed” and she just replied with “I Know”.
Controllers in the tower watched on in horror as they watched the plane struggle to gain altitude heading towards the City.
The Captain's reasoning for raising the gear was that he needed speed in the long term, he had a hill in his flight path and there was no way that he'd be able to clear the hill with the gear down slowing the plane down.
He was relying on his decades of experience and so he made the call.
The controllers watched as the plane barely gained any more altitude once the gear was up but soon the plane gained a bit of height, probably whilst still in Ground Effect.
But the 200 foot tall Panos hill was now barely a mile away. The captain did not have a choice; he pulled the nose up as the airspeed he had built up so far bled away.
The 747 Jumbo Jet cleared the hill by 9 feet.
But this was far from over, climbing to avoid the hill had cost him precious airspeed. He now had to drop the nose again to speed up otherwise the jumbo jet would drop out of the sky.
The captain decided to trade more altitude for about 6 knots in airspeed. It wasn't much but it would keep them from stalling.
At this point the jet was still so low that it barely cleared cleared some Radio and TV antennas.
But little by little Captain Migadis in his 747 managed to gain more height and speed and so then slowly turned and headed out over the sea where the air temperature dropped a little thus gaining even more height.
The crew barely able to keep the plane airborne, had been flying just 200 feet above a densely populated area of Athens. Airspeed was exceptionally slow, the FDR showing as low as 158 kts, which was not possible according to Boeing.
Later attempts in the Simulators would result in crashes at every attempt to recreate the same flight pattern.
After almost two minutes flying straight and as low barely 50m above the ground the captain was able to gain some airspeed and finally altitude up to 1,500ft over the sea.
After quickly dumping fuel over the water, the plane landed safely back at Ellinkon, some 30 minutes after takeoff.
It was discovered that the #3 engine's water injection system was mistakenly turned off prior/during takeoff, causing the engine to overheat and explode during rotation.
The water injection for engine #3 was switched to 'On' during the ground checks, but the F/E inadvertently switched it 'Off' before or during the take off.
There was a very complicated water injection system that could be used with the following early JT9D engines on the 747 :
JT9D-3A, Dry T/O rating 43.500 lbs. Wet rating 45.000 lbs.
JT9D-7 and -7H, Dry T/O rating 45.500 lbs. Wet rating 47.000 lbs.
JT9D-7A and 7AH, Dry T/O rating 46.150 lbs. Wet rating 47.670 lbs.
JT9D-7F, Dry T/O rating 46.750 lbs. Wet rating 48.650 lbs.
Water alone is specified and should contain no more than 10 (ppm) parts per million impurities.
Use of water is limited to takeoff operation up to an altitude of 8,000 feet at the minimum ambient temperatures of 32F.
Take off using water injection at max takeoff power is limited to a maximum period of 5 minutes including operation with water injection for not more than 2 1/2 minutes
On the 747-100/200 two water tanks were each built in the wing roots (left and right) and extra piping was installed for transportation of the water to the four engines (one tank for 2 engines at the same wing.) Also piping for water filling and draining of residual water after T/O was installed.
Four high capacity water pumps were feeding the engines with water.
Each engine had an adapted fuel control to cater for extra fuel when the system was activated.
System operation (747)
- When a wet rating was needed min. 2300 kgs of water was uplifted. (standpipe level was 2450 kgs)
- During Taxi-out, just before entering the runway, the system was switched on (F/E panel), the four water pumps were momentarily giving a flow indication (four green lights), check all water low press lights out. Most frequent failure at this moment : water pumps start to operate but the water shut off vlv is still (partly) open. This is called a "steam out".
The relevant engine (still at idle) gets the full water flow and stops operating and has to be restarted, after switching off the water injection system.
When entering the runway the system is now armed.
After advancing the powerlevers at approx. 1.25 EPR the system comes in, four green water flow lights illum (pilots annunciator panel), the water shutoff valves are open.
Careful monitoring of the EGT indication is crucial (one engine can suddenly revert to no water (pump failure), but still with the high (wet) fuelsetting.
After 2.30 minutes or just before water run out (indicators on F/E panel), the system is switched off.
Switching off was the most tricky part of the operation, because of the low usage of the system frequently failures occurred.
The most dangerous was that the water pumps stopped and shut off valves closed but one engine fuel control stayed at the wet fuel rating.
Before you could blink an eye the EGT exceeded the T/O limits and an expensive horoscope check or even an engine change was required.
From a KLM friends 747 crew perspective - Wet Take Offs between 1978 and 1990 on KLM 747-206B aircraft.
Most of them on the AMS-LAX NBO-AMS and AMS-IAH stretches, nearly always air-conditioning packs switched off enables more thrust from the engines.
All three of us in the cockpit were always fully aware that in fact this aircraft was underpowered when at MTOW, and the engines required a lot of extra attention during these kind of Take Offs plus at Hot and High airfields.
The engine sound of the 4 P&W JT9D-7W changed to a very low growling sound when the water injection came in at approx. 1.25 EPR powersetting. Most of the time we left the brakes on a little longer as so to gain some runway length and checked that all four green waterflow lights were illuminated.
After the"Water on" call the brakes were released.
With four growling engines it took a very long time before Vr was reached. It always looked very close to the end of the runway.
Slowly climbing with mostly MTOW (351.000 lbs) we climbed away until the water was almost running out or 2.30 minutes was reached.
Now "water off" was called by the F/E to warn us pilots for the impending thrust decrease.
Power levers were retarded a little bit, before actual stopping of the water injection system on the F/E Panel.
This was done to prevent an overboost during transition to the Dry setting.
Now GA or CLB was selected at the engine mode select panel and depending climb out procedures, GA or CLB thrust was set.
Especially after selecting the 'water injection off' and setting CLB thrust it became very quiet in the aircraft, so sometimes the captain warned the passengers before take off, that after take off the engines were only retarded and had not stopped!
KLM 747's at first had the -3AW engines but these were changed to -7W or -7AW.
I gather that also the Northwest Airlines DC-10 series 20 (as it was actually known, but monkiered as the -40 series) were fitted with PW JT9D-20/20J engines that would come with water injection and all of these DC-10 -20's were equipped with water injection and were certified with the water injection system working. The aircraft were "never" operated
AFAIK in service using the water injection.
Both the JT9-20, and -20J had been equipped with water injection but this was removed later on to save weight.
At first some of the aircraft water injection lines were removed to ease maintenance in the LH wheel well, the wing leading edges, and the engine pylons in the early 1980s.
The rest of the system was removed, other than the tank, in the early 1990s.
The water tank is mounted on the lower LH side of the fuselage, just aft of the wing, and looks like a body fairing. The drain mast for the tank is just below the aft or bulk cargo door, just left of the centerline of the belly. The tank held 600 gallons of demineralized water. There were three pumps located in the tank.
The only parts of the water injection system that were left on the engines were the fuel nozzles with the water injection ports capped off.
There was never a ' W' in the engine's designation on the data plates for either engine.
The JT9-20 was a JT9-7A that was adapted for the Douglas application, which means that the gearbox was mounted under the fan case.
The JT9-20 had a takeoff EPR of 1.46, and put out somewhere in the neighborhood of 44,000 lbs dry thrust, without water.
The JT9-20J was a JT9-7F, that had the turbine section out of the -7J, and a different fuel pump than a -20.
This engine had a takeoff EPR of 1.51, and put out roughly 48,000 lbs of thrust dry, or without water.
The -20J had a higher max EGT limit than the -20.
These two engines side by side were basically identical.
All of NWA DC-10-40s were certified at 535,000 lbs gross weight, so a -20J powered aircraft simply had more power and these aircraft were used on different routes.
In the mid 1980s P&W offered to convert the NWA DC-10-40s to JT9-7R4 power, like they did at JAL, but the aircraft was being looked at for retirement at that time, so they passed on the offer, but the NWA -40s actually stayed on for another 18 years or so.
The NWA DC-10-40s were actually DC-10-20s...Donald Nyrop, who was the CEO at the time had ordered his DC10s with the JT9s and the extended range upper and lower auxiliary fuel tanks, longer wingspan, center gear, and so on.
He then found out that Douglas was going to hang CF6-50 engines off of the same airframe, and call it a DC-10-30, well he flipped out and basically demanded that his P&W powered DC-10s be re-designated as -40s...He wanted to have the higher number, not to be outdone by the new and higher numbered -30s that would follow and show the World he had the 'better' DC-10.
While working on the DC-10-40, one would find numerous bookwork and data plates on parts of the aircraft that pertained to the P&W application, and they would be stamped DC-10-20.
The upper and lower auxiliary fuel tank access panels were also stamped "DC-10-20/-30 only".