Fogged on final

August 1, 2002

Bruce Landsberg has served as executive director of the AOPA Air Safety Foundation since 1992.

Low clouds and fog cause more problems for pilots than the big weather hazards that many of us worry about. Thunder and ice do snare a few, but the low visibility that clouds engender bends far more aluminum. The view from aloft can be deceptively good as a flight approaches an airport. At night, the problem is compounded.

In August 2000 a Piper Saratoga approached the Nantucket Memorial Airport, Nantucket, Massachusetts, just before midnight. As the airplane neared Nantucket, the pilot could see the entire island and the airport, but he filed an IFR flight plan with the Bridgeport Flight Service Station because of the "widely scattered, low ground fog" in the area.

This is the same microclimate that caught John F. Kennedy Jr. as he attempted to land at nearby Martha's Vineyard. That accident, which the NTSB attributed to spatial disorientation, occurred only 11 months earlier. It was thoroughly discussed (see " Safety Pilot Landmark Accidents: Vineyard Spiral," September 2000 Pilot), but some important points bear repeating: Pilots should always be suspicious of fog at night near large bodies of water. Moist air that cools to the dew point is fog prone. In recent years, there have been several other accidents involving low clouds and fog in the Cape Cod vicinity, where the visibility can go to zilch in a hurry.

Fatigue and stress also may have played a part in the sequence of events in August 2000. Prior to the flight, the pilot's wife had been hit by a car while crossing the street. Apparently, her injuries were minor as she was treated and released from the hospital. She and the pilot then proceeded to Penn Valley Airport in Selinsgrove, Pennsylvania. At about 9:15 p.m., they departed on a VFR flight plan eastbound toward Nantucket.

There are some similarities to the Kennedy accident, especially the delayed departure and the pressure to arrive at a destination at the end of a long day. In the Kennedy accident, the flight was delayed for several hours beyond the proposed departure time. This pilot was instrument-rated and Kennedy was not, which reduces some of the risk. In this instance, the delay was probably because of the wife's injury and emergency room visit at the hospital. Was the pilot able to stay focused on the flight despite her accident? Everyone has a different stress tolerance so this is one of those intangibles—impossible to measure but definitely in the background.

The pilot also admitted to having been awake all day. Assuming a 6 a.m. wake-up, the pilot was approaching an 18-hour day when he was called upon to make an approach into very low visibility. In retrospect, it would have been better to call it a day before departure and start fresh in the morning. Fatigue affects people differently but it has to be factored in. Fatigue has been recognized to affect judgment as well as physical flight skills.

While there have been no formal studies done on flights to "recreational destinations," there is certainly anecdotal evidence that the lure is strong to get there and play hard. Usually there is money and precious leisure time on the line. The money may be in the form of a beach house rental, nonrefundable hotel room, or your own vacation home. The desire to "be there" is human nature and one reason why certain accident situations are continuously repeated.

The pilot received an IFR clearance and approach clearance for the ILS to Runway 24. While on the approach, the pilot noticed that there was a patch of ground fog around the approach lights, but the entire runway surface and lights were visible. The Nantucket Memorial Airport weather at 11:36 p.m., just minutes prior to the accident, was reported as winds from 280 degrees at 3 knots, one-quarter mile visibility, fog, 100 feet vertical visibility, and a temperature and dew point of 59 degrees Fahrenheit. Unlike solid IMC, where the visual obscurement is already in place, there is always the hope that the forming fog will hold off long enough for the flight to get in. It's tantalizing because the conditions usually look benign.

Here is where the deception begins. The fog is shallow, perhaps only 50 to 100 feet thick, so that lights, when viewed from above, are perfectly visible. As the aircraft descends into the fog, the slant range distance looking through the obscured atmosphere increases and the lights dim rapidly. The temptation is to descend to get "underneath" the cloud. The problem with this type of condition is that the cloud goes to the surface and the fog gets thicker. There is no getting underneath. The Saratoga pilot "descended early" and the right main landing gear struck an approach light stanchion, shearing the gear assembly off.

When in IMC at night and in fog there is only one way down and that's to fanatically follow the ILS glideslope, even when you are sure that the runway is made. A smooth, steady descent brought you to decision height—why mess up a good thing? When a light stanchion meets landing gear my money is always on the ground aid—they use heavier materials than our air machines.

The airplane touched down on the runway, slid about 200 feet, and came to rest. The pilot attempted to contact Boston Center to advise them of the accident but was not successful. Detecting a fuel leak, the occupants exited the airplane. Fire broke out shortly afterward. Neither the pilot nor his wife was injured, although she must have been wondering about her luck at this point, having been involved in two accidents in one day.

It is worth noting that when an aircraft makes something other than a normal landing, immediately would be an excellent time to deplane. Don't worry about the luggage or notifying ATC, just step away from the vehicle. It's good to shut down the engine, if it's still running, by killing the mixture, the magnetos, fuel selector, and master switch. Naturally, if the fire has already started, you might dispense with those formalities.

In this accident, the pilot stacked the environmental deck strongly against himself. Fatigue, stress, fog, and night add up to a tough deal. All it takes is a lapse, like letting the aircraft slip below the glideslope when the runway is in sight and practically underneath you. We can manage many of these problems by not trying to handle everything at once. The beach will be there tomorrow.

The Federal Aviation Administration performed a flight inspection of the instrument landing system on August 26, 2000. The instrument landing system facility was "found satisfactory." The high-intensity runway lighting, touchdown zone lighting, centerline lighting, and pilot control lighting were also "found satisfactory." The approach lighting system could not be tested because of damage from the accident.—BL