Mr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 22 Posted (12 years 5 months 1 week 2 days 12 hours ago) and read 1351 times:
Those who are interested... got this from YSSY board...
This is not a drill: ordeal on Flight 222
One minute secure, the next confronted with the prospect of death, 254 passengers on SIA Flight 222 endured seven fearful minutes over NSW this week. Philip Cornford reports on their fate.
The only warning was a popping sensation in their ears. Then oxygen masks dropped out of their panels and dangled in front of their faces.
It was 5.46pm on Tuesday. In that moment, 254 passengers on Singapore Airlines Flight 222 out of Sydney were confronted with the worst fears of air travellers, a potentially life-threatening situation beyond their control. No longer passengers, they were captives of fate, powerless to do anything to help themselves. Except stay calm.
"This is an emergency. This is not a drill," a recorded message droned. For the next seven minutes, it repeated the message continuously.
In that time, the passengers - and the cabin crew - had no idea of what the emergency was, or what their fate would be. Strapped in their seats, they could only pray and hope.
"They were seven minutes of tremendous anxiety," said Singapore Airlines spokesman Stephen Forshaw.
Captain Kwon and his flight deck crew were too busy making an emergency descent to reassure the passengers, dropping the Boeing 747-400 at a vertical rate of 1.3 kilometres a minute.
The crisis was a drop in cabin pressurisation. For several minutes, cabin crew had been reporting that passengers were complaining of "popping ears" and that they had the same troubling sensation themselves - a sure sign of decompression.
Flight deck instruments confirmed their fears. Although Flight 222 was at 36,000 feet (about 11,000 metres), the air pressure inside the plane was maintained at 6,000 feet. But it had risen to 9,000 feet, there was no explanation for the fault, and it was likely to keep rising, possibly past 14,000 feet, the altitude at which humans require oxygen masks to survive.
Captain Kwon did not wait to give a warning. He activated the oxygen masks. Fortunately, the aircraft had been passing through turbulence, so passengers and cabin crew were strapped in their seat belts.
Flight 222 was 10 nautical miles south-east of Nyngan in north-western NSW, 46 minutes out of Sydney International Airport, on a seven-hour flight to Singapore. To avoid air collisions, it was locked into a flight path and had to get permission to alter course and altitude.
Captain Kwon radioed for permission to descend to 34,000 feet. Flight controllers at Air Services Australia en route centre at Tullamarine Airport in Melbourne refused permission. A Qantas plane was on the same course and altitude. They needed to maintain an air separation of 30 nautical miles and 1,000 feet.
Flight 222 was cleared to 35,000 feet. It wasn't enough. Captain Kwon requested an "emergency descent", advising air traffic control of his problem. He was told to go down to 10,000 feet. Less than a minute had passed. Captain Kwon had to lose 26,000 feet of altitude as quickly as was safely possible. He did it in six minutes.
To reduce air speed from 490 knots, he throttled back the four Pratt and Whitney engines to idle, set the speed brakes - wing panels that rise vertically on the wings, known as "spoilers" - at full on and lowered the landing gear to maximise drag.
With its nose angled eight degrees downwards, Flight 222 was going forward at 270 knots, the maximum speed a jumbo jet can fly with its undercarriage down, and dropping vertically 3,400 feet a minute, double the normal descent rate.
"Although the plane was descending at a tremendous rate, the passengers had more a sensation of forward speed," Mr Forshaw said. "They could feel the speed."
At 24,000 feet, the aircraft passed beyond radar range 15 nautical miles north-west of Nyngan but maintained radio contact until it got to 10,000 feet.
Only then did Captain Kwon inform the fearful passengers of the problem, reassuring them they were safe, there was no longer any need to use the oxygen masks. They were going back to Sydney. It was no doubt a moment of great relief. For the first time since the crisis began, the cabin crew could move freely, tending the passengers.
Three minutes later, at 5.56pm, Captain Kwon was given permission to turn his plane around.
By now, Flight 222 had a second problem. Its flight computer was malfunctioning, the likely cause of the depressurisation. But it was almost causing other instrumentation failures.
Captain Kwon switched off the auto-pilot and began flying hands on, bringing the plane back to normal. He retracted the undercarriage, closed the speed brakes and accelerated to cruising speed.
At 6.08pm, Flight 222 came back on radar, 80 nautical miles north-west of Parkes, the swing to the south completed and on course for Sydney, less than an hour's flying time away.
Thunderstorm lay ahead, to be avoided at all costs. Air traffic control directed the aircraft due south and then turned it on a heading of 85 degrees, almost due east, a straight run into Sydney over the Blue Mountains.
The crew's concern became weight. Because of faulty instruments, Captain Kwon was unable to dump fuel. The Boeing had taken off with about 90 tonnes of fuel in wing and fuselage tanks. By the time it landed it would have consumed 20 tonnes. Calculations showed the all-up landing weight - plane, passengers, cargo, fuel - would be more than about 291 tonnes. This was not a major worry, but any landing weight in excess of 286 tonnes is deemed an overweight landing and must be reported in advance.
Even though the weight was well within the Boeing's stress capabilities, any heavy landing, even only five tonnes over the limit, puts the aircraft at risk of damage. Stringent inspections are required before the aircraft can fly again.
The task is to get a heavy plane down as softly as a lighter aircraft, minimising the impact, and the extra weight makes it harder to do.
A normal landing speed is between 120 and 145 knots. But a heavier plane has to go faster, up to 170 knots, to control its descent rate to about 900 feet a minute. Going faster, it can land a lot harder. The skill is in the "flare", when the pilot pulls the aircraft's nose up in the second before touchdown, cutting speed and hopefully easing it down.
At 6.30pm Captain Kwon, now talking directly to Sydney air control, advised he would make a heavy landing. Airport and NSW Fire Brigades units went into readiness, ambulance and police were called in.
At 7.06, Captain Kwon "flared" Flight 222 onto the north-south runway. It was going so fast it required the entire runway to brake to a halt.
The passengers clapped and cheered. The crew were full of smiles. They were safely on the ground. Their ordeal was ended.
For the crew of Flight 222 and the ground operators, it had been a faultless exercise in handling a crisis.
Cx flyboy From Hong Kong, joined Dec 1999, 6533 posts, RR: 55
Reply 2, posted (12 years 5 months 1 week 2 days 12 hours ago) and read 1274 times:
Well done to the crew. We are trained over and over do to this sort of thing, although most of us never have to. It's good to see that training for this kind of thing does pay off.
Does anyone know how quickly the decompression was? It's just that putting the gear down is not in our manuals as something we have to do. If you have had an explosive decompression there is possible structural damage and putting the gear down in descent is not a good idea, as it adds a lot of unneccessary stress on the airframe. There's nothing stopping us from doing so, we just have to think about whether we want the gear down or not, and I don't mean to suggest that the SQ pilot was wrong, I am just interested in what happened.
Cx flyboy From Hong Kong, joined Dec 1999, 6533 posts, RR: 55
Reply 6, posted (12 years 5 months 1 week 2 days 7 hours ago) and read 1179 times:
Spoilers can be used on day to day flights, not only in emergencies. To give you an example, flights arriving from Chinese airspace landing in Hong Kong pass a point called SIERA, normally at FL190 or somewhere around there. If they are using runway 07 at CLK, this give only a few miles to descend. Normally you would need in the region of 70 miles to descend from that altitude. However, HKG ATC gives aircraft the option of doing a steep descent with 35-40 miles to join the ILS for Rwy 07. In this case, spoilers are used to enable a high vertical speed descent, without allowing the speed to increase to speeds where the crew would have trouble slowing the aircraft down and extending flaps. Gear is sometimes lowered at fairly high altitudes to also help slow the aircraft down.
GE From Singapore, joined Mar 2000, 320 posts, RR: 6
Reply 7, posted (12 years 5 months 1 week 2 days 5 hours ago) and read 1145 times:
Mr. BA (Alvin): Thanks a lot for the excellent report! It's great to be able to know what happened on SQ 222.
Cx Flyboy: You're a pilot right, so pls don't mind me asking a question. If gears can be used at high altitudes, can flaps be used too? I know it creates lift too, but doesn't the drag at full flaps overcome its lift? Thanks.
AJ From Australia, joined Nov 1999, 2381 posts, RR: 24
Reply 8, posted (12 years 5 months 1 week 2 days 5 hours ago) and read 1142 times:
CX, our procedures allow gear down rapid descents, but with the warning that the gear may not come back up, a real bummer if you are half way over the pacific. Time to put on the floaties. The preferred is gear up, FLCH, Mmo/Vmo, flt detent on the speedbrake, idle thrust down to FL140. Pretty similar to yours?