These pages often discuss the tricks and traps of night flying, stressing along the way the only real difference between doing it after the sun goes down instead of in the daytime is you often cant see too well. As a result, we have to depend less on the seat of our pants and more on the “system” to get us home.
The good news is theres more “system” than ever before. Infrared vision entered the high-end business jet cockpit a few years ago; its already trickling down to turboprops and the occasional well-equipped piston. Meanwhile, innovations like the synthetic vision technology are available on Cirrus Design airplanes equipped with the Perspective avionics suite.
Even without all these tools, using data from the IFR system-minimum en route altitudes, approach and departure procedures, for example-will help keep us out of the weeds, also.
The bad news is we still make dumb mistakes at night. Some of those mistakes result from known limitations of the human eye and should be easy both to identify and overcome. Other mistakes are more subtle and, in a way, a related to the eyes shortcomings but primarily result from there being fewer visual cues at night, often when we need them most. Like when landing.
Too often, nighttime mistakes take on an “if only” characteristic: If only the pilot had waited to begin that descent, or if only s/he realized the runway lights disappeared because there was a hill between them and the airplane. Throw in the fact most of us are not functioning with peak efficiency at night, that theres an urgency to get home and get in bed, or that many night flights take place after the pilot or crew have put in a full day of work-whether the work is flying or sitting at a desk doesnt matter-and really bad things can happen.
Even when we work within the system of procedures established to help ensure safe operations, night flight seems to bring with it the need to search out and accept shortcuts. The nighttime visual approach is one such shortcut. When used correctly, there usually isnt a problem.
Background
On February 6, 2007, at 2104 Mountain time, a Beech Model 200 Super King Air was substantially damaged when it collided with sparsely populated mountainous terrain approximately 13 nm north-northwest of the Gallatin Field Airport (BZN) in Belgrade, Mon. Its three occupants, an airline transport pilot, flight paramedic and flight nurse, were killed. The Part 91 EMS positioning flight was operating IFR; instrument conditions prevailed at the departure airport and dark night visual conditions were present at the destination.
At 2057, the pilot was cleared to descend at his discretion from 15,000 feet to 13,000 feet. A satellite-based flight-tracking service used by the operator later indicated the airplane started a descent from 15,000 feet msl approximately 42 nm north of the airport. The pilot acknowledged his clearance stating, “…Ive got the airport in sight at BZN requesting a visual approach.” At 2100, the pilot was cleared for the visual approach to the BZN airport. Radio contact was lost shortly thereafter.
Investigation
The wreckage was located about 2230 that evening, approximately 80 feet below the peak of a ridge rising to approximately 5700 feet. From the first identified point of contact with terrain, the debris path tracked over the crest of the ridge and continued down the far side in a south-southeast direction for approximately 1575 feet.
Review of pilot records, and subsequent conversations with the operator, indicate the pilot had flown this particular route of flight and was familiar with the terrain. The airplane was equipped with an Enhanced Ground Proximity Warning System (EGPWS), including a pilot-activated inhibit switch. The airplane was not equipped with a TAWS graphic display. Post-accident attempts to recover data from its non-volatile memory were unsuccessful.
Weather at the destination airport, sited at 4471 feet msl, at 2056, was wind from 300 degrees at four knots and unrestricted visibility at 10 miles. There was an overcast ceiling at 11,000 feet. The moon that night, just past full, would not rise until 2234. Radar services were not available at BZN prior to commissioning of a surveillance radar system in April 2007.
Post-accident examination of the wreckage disclosed no evidence of a mechanical malfunction prior to impact.
Probable Cause
The National Transportation Safety Board determined the probable cause(s) of this accident to include: “The pilots failure to maintain an adequate altitude and descent rate during a night visual approach. Dark night conditions and mountainous terrain are factors in the accident.” The Boards finding doesnt leave us much to argue with.
Ultimately, a pilot familiar with the area and with the destination airport disregarded one of the tips pilots learn when they first tackle night flying: Keep the airplane high-higher than normal, perhaps-until youre positive there are no obstructions between you and the runway. Then begin your letdown.
One of the reasons for this admonition is the tricks the human eye can play with depth perception. At night, the eye wants us to believe were higher than we really are, luring us down to a lower altitude further from the runway than we would normally fly in the daytime.
The other reason is really basic: We simply cannot see unlit objects-like dark hills in our approach path-at night, no matter how good we think our night vision is. This presumes, of course, we dont have any “help” in the form of night vision equipment or a synthesized presentation of whats outside the window.
One of the curiosities about this accident is why an aircraft equipped with EGPWS still was able to find its way into a hillside. Its possible the pilot received a terrain warning from the device, even while he still had the airport in sight, and inhibited it. Probably not long after that, with his head down in the cockpit configuring the airplane for landing, the hill slid up to block the pilots visual cues and the distant airport.
