Safety Pilot Landmark Accident: Flameout

On December 28, 1978, United Airlines Flight 173, a McDonnell Douglas DC–8-61, departed Denver, Colorado, with 181 passengers and eight crewmembers bound for Portland, Oregon. The flight-planned time was two hours and 26 minutes, with a scheduled arrival in Portland at 5:13 p.m. PST. The total amount of fuel required was 31,900 pounds. The airplane departed with 46,700 pounds of fuel on board, which included the FAR requirement for fuel to destination plus 45 minutes and a company contingency of about 20 minutes. The weather was good VFR.

 

Abnormal gear

Around 5:10 p.m., as the flight was descending through 8,000 feet, the first officer, who was flying, asked for approach flaps and landing gear. The captain recalled, “It was noticeably unusual and [I] feel it seemed to go down more rapidly. As [it is] my recollection, it was a thump, thump in sound and feel. I don’t recall getting the red and transient gear-door light. The thump was much out of the ordinary for this airplane. It was noticeably different.”

At 5:12:20 p.m., Portland Approach requested, “United One-Seven-Three Heavy, contact the tower, one-one-eight-point-seven.” The flight responded, “Negative, we’ll stay with you. We’ll stay at five. We’ll maintain about 170 knots. We got a gear problem. We’ll let you know.” The flight was cleared down to 5,000 feet and given delaying vectors.

Contributing to the accident was the failure of the other two flight crewmembers either to fully comprehend the criticality of the fuel state or to communicate their concern to the captain. According to the NTSB, “For the next 23 minutes, while Portland Approach was vectoring the aircraft in holding south and east of the airport, the crew discussed and accomplished all of the emergency procedures available to them to ensure the gear was down. The lead flight attendant was briefed and told to prepare the cabin for a possible emergency evacuation. About 5:38 p.m. the crew contacted the United Airlines maintenance control center in San Francisco, California, and the captain explained the situation while they continued to troubleshoot.”

At that time the captain reported 7,000 pounds of fuel on board and that he planned to hold for another 15 or 20 minutes to prepare the passengers for emergency evacuation. At 5:44 p.m. United maintenance asked, “OK, United one-seventy-three, you estimate that you’ll make a landing about five minutes past the hour. Is that OK?” The captain responded, “Yes, that’s good ballpark. I’m not gonna hurry the girls [presumably referring to the flight attendants]. We got about 165 people on board and we…want to…take our time and get everybody ready and then we’ll go.” With that ETA, there probably would have have been less than 15 minutes of fuel remaining.

At 5:50 p.m. the captain asked the flight engineer to, “Figure about another 15 minutes.” The first officer responded, “Fifteen minutes?” To which the captain replied, “Yeah, give us three or four thousand pounds on top of zero fuel weight.” The flight engineer responded, “Not enough. Fifteen minutes is gonna really run us low on fuel here.” It was the strongest statement he would make.

At 6:06 p.m., the lead flight attendant reported the cabin was ready for an emergency landing. (This was one minute after the captain said they would be landing.) The aircraft was 17 miles south of the airport heading southwest. The captain said that they would be landing in about five minutes.

Flameout!

Just then the first officer said, “I think you just lost number four.”

At 6:06:46 p.m., the first officer told the captain, “We’re going to lose an engine.” The captain replied, “Why?” At 6:06:49 p.m., the first officer again stated, “We’re losing an engine.” Again the captain asked, “Why?” The first officer responded, “Fuel!”

At 6:07:12 p.m., the captain requested “Clearance for an approach into Two-Eight Left, now!” This was the first request for an approach clearance from Flight 173 since the landing-gear problem began. At 6:07:27 p.m. the flight engineer stated, “We’re going to lose number three in a minute, too.” The captain responded: “You got a thousand pounds. You got to.”

The flight was now about 18 miles out and headed toward the airport. At 6:13:21 p.m., the flight engineer stated, “We’ve lost two engines, guys.” At 6:13:38 p.m., the captain said, “They’re all going. We can’t make Troutdale [a small GA airport nearby].” The first officer replied, “We can’t make anything.” At 6:13:46 p.m. the captain told the first officer, “OK. Declare a Mayday.” The first officer advised, “Portland Tower, United One-Seven-Three Heavy, Mayday. We’re…the engines are flaming out. We’re going down. We’re not going to be able to make the airport.” About 6:15 p.m., the DC–8 crashed into a wooded area of suburban Portland about six nautical miles southeast of the airport. There was no fire.

Two crew members (including the flight engineer but not the captain) and eight passengers died. There were 23 severe injuries and 156 with little or no injury.

The crew

The 52-year-old captain had been employed by the airline since 1951. He upgraded to captain in 1959. At the time of the accident, he had 27,638 total flight hours, 5,517 of which were as a captain in the DC–8. He had passed his last proficiency check in September 1978.

The 45-year-old first officer was hired by the airline in 1965. He upgraded to a DC–8 first officer in 1978. He had 5,209 total flight hours but was relatively new to the DC–8, with only 247 hours. He had passed his proficiency check in June 1978.

The 41-year-old flight engineer was employed by the airline in December 1967. He upgraded to a DC–8 second officer in January 1975. He had 3,895 total flight hours as a flight engineer, 2,263 of which were in the DC–8.

The aircraft

The precipitating event was the failure of the right main landing gear’s retract cylinder assembly. The assembly’s main purpose is to raise the landing gear during the retract cycle, but its hydraulic action also acts to control the rate of extension, keeping the gear from free-falling to the down-and-locked position. A piston rod failed because of corrosion. McDonnell Douglas had issued a service bulletin to address corrosion, which had been accomplished—and, later, to modify the cylinder, but that had not been done. The aircraft was 10 years old, young by GA standards, but it points out the importance of maintaining flight-critical systems.

There was some discussion in the accident report regarding the fuel gauges’ accuracy and a modification of the fuel system, but the NTSB determined that the systems were reporting correctly.

NTSB probable cause

“The National Transportation Safety Board determined that the probable cause of the accident was the failure of the captain to monitor properly the aircraft’s fuel state and to properly respond to the low fuel state and the crewmember’s advisories regarding fuel state. This resulted in fuel exhaustion to all engines. His inattention resulted from preoccupation with a landing-gear malfunction and preparations for a possible landing emergency. Contributing to the accident was the failure of the other two flight crewmembers either to fully comprehend the criticality of the fuel state or to communicate their concern to the captain.”

The NTSB analysis noted that the captain delayed contacting maintenance for about 28 minutes from the time of gear malfunction. After speaking with company maintenance personnel, the flight should have turned inbound to land. This would have occurred 30 to 40 minutes after the initial gear problem and landing would have occurred with about 15 to 20 minutes of fuel remaining.

Commentary

This accident led to the formal establishment of crew resource management (CRM) and helped the airline industry move beyond a mindset that was prevalent at the time—Rule 1: The captain is never wrong. Rule 2: If the captain is wrong, see Rule 1. Good captains, however, have always understood that the other crewmembers are not there just for aggravation.

The reality is that in the heat of battle, distraction sometimes creeps into the equation and snares the best of us.Had the flight engineer said something such as, “Captain, we will run out of fuel in about 15 minutes and we will crash; we need to land right now,” chances are that everyone on the flight deck would have had a clearer picture of the urgency.

Although the culture has generally changed, the CRM system is only as good as the willingness of crewmembers to apply it. Avianca Flight 52, a Boeing 707, crashed because of fuel exhaustion in 1990. Asiana 214, a Boeing 777, crashed on a visual approach to San Francisco in 2013. In both cases, the lack of internal crew communication led to fatalities and the destruction of fully functioning aircraft. Thousands of accidents are prevented by the implementation of CRM, but the point is that accidents are prevented one at a time—and each incident requires the individuals involved to perform.

For GA pilots there are fewer resources, but there is still plenty of help available. Regarding fuel, it’s going to be your call, but here are a few thoughts. First, know how much fuel is actually on board the aircraft; without that, you’re guessing. Full tanks or using internal tank references, such as tabs, provides certainty. If the tanks are less than full, it’s more complicated. Be wary of someone telling you they only flew for half an hour! A dipstick is a great idea and all aircraft ought to be delivered with one, or subsequently equipped (calibration can be a bit of a nuisance). However, the aircraft must be parked on a level spot for any degree of accuracy.

Fuel totalizers are accurate in measuring flow and should be high on any list of upgrades—but again, the starting point must be known. The gauging on light aircraft may be variable, especially older ones. Flight time is an excellent measurement with a few caveats. It’s dependent upon knowing the starting point (above), knowing the burn rate (both in climb and cruise), and leaning appropriately.

An alternate plan should include some easy choices. When first starting to get uneasy about fuel, if working with ATC, declare minimum fuel. If it goes beyond that, declare an emergency. The AOPA Air Safety Institute recommends the Golden Hour, which means the aircraft will always be on the ground when down to one hour of fuel remaining. If there is a slight miscalculation for any reason, it won’t matter.

Some pilots believe the captain was unfairly tagged with the responsibility and that the gauges were faulty. On January 2, 1999, The Register-Guard in Eugene, Oregon, had a story regarding the reunion of the passengers and crew of Flight 173. “The gratitude of the survivors and their families clearly touched Capt. Malburn McBroom. The former United Airlines pilot wept Monday night during a standing ovation from nearly 200 people. The gesture celebrated the fact that 179 people aboard Flight 173 survived the 1978 crash landing. But even in the applause, the same old question haunted McBroom: What about the 10 who did not survive?” The article discusses the terrible burden that McBroom carried, leaving him “a broken man.”

In magazines, hangars, and coffee shops, pilots discuss accidents in clinical terms, reassuring ourselves that we never would be so stupid or careless. The reality is that in the heat of battle, distraction sometimes creeps into the equation and snares the best of us. The planned reaction and periodic refresher training is, as always, a good antidote. When faced with an abnormal situation, remember that fuel and flight time are finite.

Bruce Landsberg is senior safety adviser for the AOPA Air Safety Institute.