Human Factors: Planes, trains, and…

It was mid-February 2023 when the pilot and his buddy flew into Dunham Field (1XS1), a private grass-strip airport just northeast of Crosby, Texas, on the east side of Houston.

The purpose of the trip was to talk to an A&P mechanic based there about getting an annual for the 1967 Cessna 172 model the pilot recently purchased and having an autopilot installed. Time was of the essence, as the annual was due at the end of the month.

Dunham sits at an elevation of 60 feet and has a 2,700-foot-long by 100-foot-wide grass strip, although it was apparently both rough and soft.

The pilot later told the NTSB investigators: “I had visited the A&P by car previously, and had reservations about the airstrip, but the prospect of saving money and a nice day overrode my gut feelings.”

And the day did start off nice.

The pilot and his friend flew from the 172’s home base at West Houston Airport (KIWS), on the west side of Houston, over to Baytown for lunch, then up to the private field. The distance between KIWS and Dunham Field is only 40 miles as the crow flies — only the crow would never get clearance through the Bravo that sits smack dab in the middle between the two uncontrolled airports.

After talking with the mechanic, the visiting pair took off again, and the pilot’s reservations about the airstrip proved devastatingly correct.

The Accident

The pilot asks his passenger, a fellow pilot — both higher rated and more experienced with grass strips — to handle the takeoff, but the other pilot declines, which gives the pilot “second thoughts,” but he proceeds anyway.

And it doesn’t go well from the start.

“The bumpy, soft surface seemed to impede our speed somewhat,” he later wrote in his report to the NTSB, “so I decided to perform a soft field takeoff in ground effect.”

This wording suggests that he didn’t use the soft field technique from the get-go.

He went on to report, “A bit past the halfway point, the slow build up of speed was very concerning.”

The certificated pilot passenger, who declined to handle the takeoff, now suggests aborting the attempt, but the pilot doesn’t think he has the room left.

There are wires at the end of the runway they somehow manage to miss, but as they near a set of railroad tracks some 300 feet from the end of the runway, wouldn’t you know it? A freight train is passing by.

“I did my best to gain enough altitude to clear the train, but the wheels just clipped the top of a boxcar,” the pilot wrote in his Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1.

He added that “another 12-18 inches and we would have cleared.”

Or, I guess, if there hadn’t happened to have been a train passing by at just that time, they would have been fine.

After catching its landing gear on the passing train, the 172 somersaults and smacks down — inverted — next to the tracks, perpendicular to its original direction of flight, its tail bent and nearly sheared off, its engine separated from the fuselage. The wreckage is no more than a plane-length from the tracks.

So much for saving some money.

The pilot-rated passenger is able to depart the cabin “under his own power.” Then the passenger and a pilot from the airport extract the accident pilot from the wreck. He’s seriously injured and is transported to a local hospital.

The Pilot

The accident pilot was a 75-year-old male who held a recreational pilot certificate with BasicMed.

He had 190 hours total time, close to 15 in the make and model, with a dozen hours in the last three months, and five in the last 30 days.

The Final Moments

A local pilot observing the takeoff later told the NTSB that it did not appear that the accident pilot used full throttle during the first part of the takeoff which, if true, is odd, as the pilot’s report of the accident suggests he started with a short field technique, then tried to switch to soft field halfway down the runway. If he started with a short field, he should have been at full power before releasing the brakes.

As a refresher: For a short field takeoff, you get as close to the edge of the end of the runway as you can (which the accident pilot didn’t), hold brakes, throttle up to full power (which he might or might not have done), release, liftoff at the usual airspeed, and climb out at Vx.

For soft field you never stop moving from taxi, throttle up as soon as you are lined up, lift off into ground effect, and accelerate to flying speed while skimming the grass.

I wonder if he had deployed a proper soft field from the start, would he have gotten off that soft runway in good order and cleared the train?

The local pilot stated that the Cessna 172 was moving so slowly during the first part of the takeoff run that he thought the accident pilot was taxiing to the far end for a takeoff from that side.

The NTSB

The NTSB ran the numbers and calculated the aircraft should only have needed 1,200 feet of runway to clear a 50-foot moving train…uh…50-foot obstacle.

Investigators stated in their final report that, “It is likely the pilot’s delayed decision to perform a soft-field takeoff procedure resulted in the airplane not adequately accelerating to a proper airspeed and climb rate.”

As a postscript, the accident pilot wrote that the passenger pilot — after it was all over — estimated that they had about 2,200 feet of runway from where they chose to start the takeoff run. By the book, it should have been enough, but why piss away 500 feet of runway when you are already concerned about conditions?

Analysis & Discussion

In his safety recommendation, the pilot suggests that when a field is both short and soft a pilot should consider combining the techniques. While there is no definition of what makes a short field well… short… I personally wouldn’t regard 2,700 feet at sea level to be particularly short — and his home base is only a third longer at 3,953 feet.

That said, while most soft fields are also short, soft technique should trump all else when flying off of grass. That’s what it’s for. The technique frees the airplane from the friction-dense and potentially speed-robbing bumpy nature of non-paved strips.

Could the bumpy nature of the field have contributed to the lack of full power reported by the local pilot on the ground? Is it possible that the beating the accident pilot was taking from the rough surface, plus his natural concern for his new ride, led him to subconsciously avoid full throttle?

And what to make of a pilot who declines to assist in a dicey takeoff, but straps in as a passenger anyway?

Other things that I really wanted to know, but could not find out, include:

• Did the train stop?
• Would the engineers even have had any way of knowing that they had just been clipped by an airplane?

Also, the NTSB’s responsibilities include rail accidents, but it’s a different “department.” Did both sets of investigators get involved? That’s a lot of feds at your hospital bed.

In his safety recommendations, the pilot stated that, “for unfamiliar airports, ask locals about hazards, other special circumstances.”

I agree this is sound advice, and he actually did do this, but I’m not too sure about his next idea: “Even though POH doesn’t recommend flaps for takeoff, perhaps pop in 10° when airborne for a quick climb.”

The Takeaway

The key takeaway is one I thought everyone knew, but apparently not: When on grass, use the soft field technique regardless of runway length.

Secondly, never let delusions of saving money override “gut instinct.” Gut is almost always right, and there’s nothing cheap about aviation.

The Numbers

Want to read more? Download the NTSB’s final report here or view the items on docket here.