Air Illinois 710
Accident Case Study
Figure: Air Illinois 710, from Aviation Safety Net
- Date: 11 October 1983
- Time: 20:53
- Type: Hawker-Siddeley HS-748-FAA Srs. 2A
- Operator: Air Illinois Airlines
- Registration: N748LL
- Fatalities: 3 of 3 crew, 7 of 7 passengers
- Aircraft Fate: Destroyed
- Phase: Approach
- Airports: (Departure) Springfield-Capital Airport, IL (SPI/KSPI), United States of America; (Destination) Carbondale-Southern Illinois Airport, IL (MDH,KMDH), United States of America
[NTSB AAR-85-03, ¶1.1.]
- At 2021:14. Flight 710 contacted departure control and informed the controller that it was climbing through 1,500 feet. The departure controller advised the flight that he had it in radar contact, cleared it to climb to and maintain 5,000 feet, and cleared it to proceed direct to Carbondale after it received the Carbondale VOR (very high frequency omni directional radio) signal on its navigational radio. Flight 710 acknowledged receipt of the clearance.
- At 2021:34, Flight 710 informed the departure controller that it had experienced a "slight electrical problem" and that it would keep the controller "advised." The controller asked the flight if it was going to return to Springfield, and the flight reported that it did not intend to do so.
- At 2022:10, the flight told departure control that "We'd like to stay as low as we can," and then it requested and was cleared to maintain 3,000 feet. The controller asked the flight if he could provide any assistance, and the flight responded, ￼ ..we're doing okay, thanks."
- At 2023:54, the first officer told the captain that "the left (generator) is totally dead, the right (generator) is putting out voltage but I can't get a load on it." At 2024:26, the first officer reported, "zero voltage and amps (amperes) on the left side, the right (generator) is putting out twenty-seven and a half (volts) but I can't get it to come on the line." At 2025:42, he told the captain that the battery power was going down "pretty fast."
- At 2026:03, Flight 710 reported to the Kansas City ARTCC and told the center controller that they were at 3,000 feet. Shortly thereafter, the first officer reported that the battery voltage was 22 volts.
- At 2027:24, the captain called Kansas City center and stated that he had an "unusual request." He asked clearance to descend to 2,000 feet "even if we have to go VFR." He also asked the controller to "keep your eye on us if you can." The controller told the flight that he could not clear it to descend because 2,000 feet was below his "lowest usable altitude." He also told the flight that if he requested VFR and then descended to 2,000 feet he did not believe he could maintain radar contact. The captain thanked the controller and continued to maintain 3,000 feet. During this conversation, the first officer reported that the battery voltage was 22.5 volts.
- At 2028:45, the captain said "Beacons off. ..," and, at 2028:46, he said, "Nav (navigation) lights are off." At 2031:04, the first officer reminded the captain that Carbondale had a 2,000-foot ceiling and that the visibility was 2 miles with light rain and fog."
- At 2033:07, the flight attendant came forward and the captain asked her if she could work with what she "had back there." The flight attendant reported that the only lights operating in the cabin were the reading lights, the lights by the lavatory, the baggage light, and the entrance lights. The captain instructed her to brief the passengers that he had turned off the excess lights because the airplane had experienced "a bit of an￼electrical problem. . . ." but that they were going to continue to Carbondale. The flight attendant requested the Carbondale estimated time of arrival (ETA) and the first officer said they would arrive "about on the hour."
- At 2038:41, the first officer told the captain, "Well, when we. .. . started losing the left one I reached up and hit the right [isolate button] trying to isolate the right side [be] cause I assumed the problem was the right side but they [the generators] both still went off."
- At 2044:59, in response to the captain's request, the first officer reported that the battery voltage was 20 volts. At 2049:23, Kansas City center requested Flight 710 to change radio frequencies. The flight acknowledged the request, which was the Last radio communication received from Flight 710.
- At 2051:37, the first officer told the captain, "I don't know if we have enough juice to get out of this. At 2052:12, the captain asked the first officer to watch my altitude, I'm going to go down to twenty-four hundred (feet)." He then asked the first officer if he had a flashlight and to have it ready. At 2053:18, the first officer reported, "We're losing everything, .. down to about thirteen volts," and, at 2053:28, he told the Captain the airplane was at 2,400 feet. At 2054:00, the captain asked the first officer if he had any instruments. The first officer asked him to repeat and at 2054:16, the captain asked, "Do you have any instruments, do you have a horizon [attitude director indicator]?"
- About 2051, Kansas City center lost radar contact with Flight 710. The last confirmed radar return from Flight 710 occurred near the Centralia, Illinois VORTAC located about 40 nmi north of the Southern Illinois Airport. The accident occurred during the hours of darkness. The wreckage of the airplane was found in the rural area about 6 nmi northeast of Pinckneyville, Illinois, at 38°9' north latitude, 89°19' west longitude. Three crewmembers and seven passengers were killed in the crash.
[NTSB AAR-85/03, ¶2]
- The Safety Board's investigation disclosed that the d.c. electrical power from the airplane's two engine driven generators was lost within about 2 minutes after takeoff from Capitol Airport, Springfield, Illinois. Despite the fact that the weather at Capitol Airport was above VPR minimums, the fact that the estimated time en route to his destination at Southern Illinois Airport, Carbondale, Illinois, was 45 minutes, and the fact that the flight crew knew that the reported weather at Southern Illinois Airport was below VFR minimums, the captain elected to continue to his destination.
- The Safety Board believes that by 2025:42 it should have been obvious to the captain that he had to rely solely on the airplane's batteries for electrical power. At 2025:42, Flight 710 was about 6 minutes from Springfield and about 39 minutes from Carbondale.
- The description of the captain's flying habits provided by his peers indicated that he placed a high priority on maintaining flight schedules.
[NTSB AAR-85/03, ¶3.1]
- The left generator's spline drive shaft sheared shortly after takeoff.
- The first officer erroneously isolated the right generator from the airplane electrical distribution system when the left generator failed.
- Power from both generators was lost about 2 minutes after takeoff from Springfield.
- The right generator was capable of producing electrical power throughout the flight. However, the first officer was unable to restore i t on the airplane's electrical distribution system.
- The captain elected to continue to Carbondale rather than return to Springfield. The time required to fly to Carbondale was about 39 minutes and to Springfield, 6 minutes.
- The captain's decision to continue was affected by self-imposed psychological factors which led him to an inaccurate assessment of the airplane's performance capability without generator power and the risks involved in continuing the flight to the more distant destination airport.
- The flight crew did not use proper procedures to cope with the electrical emergency.
- The flight crew did not reduce the load on the batteries to the lowest possible value. Despite this, the batteries produced electrical power for about 31 minutes.
- The procedures for coping with and the consequences arising out of the failure of both generators were not covered adequately in the Air Illinois recurrent training program. This inadequacy was not detected during FAA surveillance inspections.
[NTSB AAR-85/03, ¶3.2] The National Transportation Safety Board determines that the probable cause of the accident was the captain's decision to continue the flight toward the more distant destination airport after the loss of d.c. electrical power from both airplane generators instead of returning to the nearby departure airport. The captain's decision was adversely affected by self-imposed psychological factors which led him to assess inadequately the airplane's battery endurance after the loss of generator power and the magnitude of the risks involved in continuing to the destination airport. Contributing to the accident was the airline management's failure to provide and the FAA's failure to assure an adequate company recurrent flightcrew training program which contributed to the captain's inability to assess properly the battery endurance of the airplane before making the decision to continue, and led to the inability of the captain and the first officer to cope promptly and correctly with the airplane's electrical malfunction.
NTSB Aircraft Accident Report, AAR-85/03, Air Illinois Hawker Siddley HS 748-2A, N748LL, Near Pinckeyville, Illinois,, October 11, 1983