OSHKOSH - A temporarily closed runway and relatively low ceilings caused a glut of aircraft to arrive into Wittman Airport at the same time Sunday, many of which flew unstable approaches by traditional metrics. 

Ground observers of traffic arriving on Runway 27, one of three “runways” in operation Sunday afternoon, witnessed numerous close-calls, including would appear to be one or more near collisions, as a mix of general aviation, business aviation and  “warbirds” funneled into the airport, with the general aviation aircraft often flying “base” legs at very low altitude before sharply turning 90 degrees to line up with the runway. Typically a stable approach requires the aircraft to be in landing configuration, speed, glideslope and desired vertical speed at 500 ft. above the runway.

“I’ve flown into Oshkosh on a Sunday afternoon for 20 years, and it’s the worst I’ve ever seen,” says Avidyne president Dan Schwinn of his arrival to Wittman as traffic recovered from an early afternoon landing incident in which the gear of a Mooney appeared to collapse after a bounced landing.

Runway 27 was closed for approximately one hour. Meanwhile, air traffic controllers advised inbound aircraft to either fly to an alternate airport or to hold to be sequenced into the flow of aircraft landing on the North-South runways (the airport uses a parallel taxiway as the second North-South runway during the show). “I hope they have a post-mortem to figure out how they got into it,” says Schwinn, a member of the board of directors for the Experimental Aircraft Association (EAA) who is also involved in industry efforts to stem the fatal accident rate.

In an environment where loss-of-control (LOC) accidents represent the majority of fatal accidents for general aviation pilots – and where the FAA, NTSB and industry are going to great lengths to reduce the numbers, in part by promoting stabilized approaches – the Oshkosh arrivals stood out as business as usual.

“I don’t think there’s ever a time you should be flying close to the ground in an unstable manner,” says George Perry, senior VP for the Aircraft Owners and Pilots Association Air Safety Institute. He says several of his friends flying to the airport decided to divert elsewhere when the disruptions occurred on Sunday. Perry has been a vocal supporter of a circular approach, similar to what is used by the military, where aircraft are configured near or fully for landing on the downwind leg, and perform a gentle 180-degree turn to the runway. “If the aircraft is not on the stabilized approach criteria at 500 ft. above the runway, the pilot should (perform a go-around),” says Perry. Few pilots on Sunday asked for go-arounds.

The EAA and the FAA developed a 30-page Notice to Airmen (Notam) that pilots were encouraged to read before flying into Wittman for the AirVenture show. The document spells out all the various permutations of arrival scenarios, encouraging pilots to use other airports if they are “not comfortable with OSH AirVenture procedures.” The Notam also tells pilots not to perform “S-turns” when trying to maintain 0. 5mi. minimum spacing behind an in-trail aircraft, but rather to break off the approach and return to the starting point.

Nowhere in the document does the FAA or EAA define an unstable approach or discuss when to abort an approach. Instead the Notam tells pilots to use “extra caution” to maintain a safe airspeed and to be “prepared for a combination of maneuvers that may include a short approach with descending turns, followed by a touchdown at a point specified by Air Traffic Control (ATC) which may be almost halfway down the runway.” The EAA also points pilots to a Safety Alert that the NTSB issued for the AirVenture show, cautioning pilots that the “major fly-in event environment” with “hundreds of thousands of people watching, may create pressure for pilots to continue an approach that they are uncomfortable with rather than go around.”

That advice is based in part on a stall-spin LOC accident at last year’s AirVenture of a Piper Malibu turning base leg to final on Runway 27 at less than 200 ft. above the ground. The NTSB in its analysis of the accident found that the controllers had provided the proper clearance between the Malibu and a departing aircraft on the same runway (the FAA has a waiver to reduce the minimum horizontal spacing over the runway to 1,500 ft. for the show compared to the normal 3,000 ft.), but that the pilot did not perform a go-around despite the unstable approach.

Based on its analysis, NTSB investigators asked the EAA and FAA to insert comments in this year’s Notam about the reduced separation for the show to inform pilots “not be afraid to ask to go-around,” says Scott Dunham, an NTSB national resource specialist for ATC. NTSB’s recommendation to expand the landing pattern with a wider downwind leg to give pilots more time on the base leg was rejected since controllers would have difficulty spotting the aircraft visually, says Dunham. Given the congestion at the airport, controllers, all of whom are volunteers, visually spot aircraft using binoculars from various locations on and around the airport. Dunham says there are approximately 86 controllers at the show, most of whom are highly experienced. “It takes four years to be fully qualified to work here,” he says.

This year’s Notam alerts pilots to the reduced separation standards and tells pilots to “notify ATC immediately” if a go-around is needed, but does not discuss go-arounds in relation to unstabilized approaches. Dunham says there are a variety of reviews during and after the show to improve the safety of operations here.

Earl Weener, the NTSB board member who most closely follows the loss-of-control issues for general aviation, told Aviation Week that pilots must be prepared “for something unexpected” when operating here during the show, a key reason for reading the NTSB’s safety alert and the Notam beforehand. Weener flew here commercially this year, but has flown his Bonanza to Oshkosh several times in the past.

“It’s the way Oshkosh has been done for years,” he says of the reduced separation standards and high intensity operations. “There’s some degree of acceptance of the uniqueness of the approach.”