Understanding dangers associated with winter mountain weather
Better education, familarity and thorough planning contribute to safe flight.
A sample GIVSP balked landing procedure for ASE illustrates—when reviewed with the ASE VOR/DME or GPS C approach—how a powerful fast airplane can maneuver tightly in a dead-end valley clear of terrain and back onto what is essentially the published missed approach/departure procedure, significantly reducing “pucker factor.”
There is a reason many mountain airports are closed after sunset and have approach procedures that are not authorized at night. “Focus on flying within your own limitations,” says Gardner. “Keep ego out of it and understand your personal envelope.”
As Chilton explains, “You can’t expect to fly to the missed approach point and land straight in at places like Aspen.” Many experienced operators establish personal or company VDPs prior to published MAPs to allow for a more stabilized descent at 3–4° instead of the 6+% that may be required in the published procedure.
Consider carefully before circling, as this maneuver in tight mountain valleys increases risk significantly, especially in IMC conditions. Many mountain airport approaches prohibit circling. “Do your best to avoid diving in a nose-down attitude at the runway,” advises Chilton, “instead thinking about your tools (gear, spoilers, flaps etc) to sink at the runway in a stabilized normal approach attitude.”
“You don’t have to fly all the way down to published minimums,” says Gibson, who recommends applying some common sense and considering a higher-than-published company or personal MDA at which to level off.
If you can’t get the runway in sight visually, simply continue to the MAP and fly the missed as published. As Gibson notes, “the further you go down into a valley the further it is to climb out.” It goes without saying that pilots must also pay special attention to missed approach climb gradients and ensure they can meet the required climb performance even single-engine.
They should be familiar with the missed approach so they’re not caught off guard. As Chilton notes, pilots often struggle with this. Fully brief complex missed approach procedures and be prepared to execute your plan so you don’t get caught unprepared.
Avoid the temptation to tanker fuel if it will make meeting missed approach and balked-landing climb gradients difficult to attain. According to Gibson, “the biggest pucker factor is if you are below MDA, or even in VMC, and have to make a balked landing.”
Disabled aircraft, snow removal equipment on the runway, wildlife or an unstabilized approach can all lead to a balked landing. While FAA doesn’t require or publish balked-landing procedures, a properly prepared flightcrew must consider the possibility. “Speed control and turn radius are key when executing a proper balked landing at a dead-end valley like on the approach to ASE,” recommends Landis.
An additional level of safety can be provided by a customized balked-landing procedure designed for your aircraft—an escape plan. Several providers can assist with this, including Colorado-based Aircraft Performance Group (APG). A sample balked landing procedure for ASE is shown on this page.
This GIV balked landing illustrates—when reviewed with the ASE VOR/ DME or GPS C approach—how a powerful fast airplane can maneuver tightly in a dead-end valley clear of terrain and back onto what is essentially the published missed approach/ departure procedure, significantly reducing “pucker factor.”
Challenges don’t end once the aircraft is on the ground. If hangarage is unavailable and you decide not to reposition, keep a close eye on the weather. Pack appropriate clothing and footwear to spend time on cold and icy ramps. Give yourself plenty of time to secure your aircraft, and especially to prepare for departure.
Consider the possibility of heavy snow accumulation if the airplane is left outside. “It’s possible to have a tail strike with heavy snow loading on turboprops and jets,” says Atlantic Aviation ASE General Mgr Fred Mosher.
If you have an APU on cold days, be sure to get it up and running early. And warm cabin and cockpit thoroughly before turning on sensitive modern avionics equipment—but be aware of APU curfews. For smaller, non-APU-equipped aircraft, consider running an engine to heat the interior before powering avionics equipment.
Deicing can be cumbersome and expensive, but it’s a fact of life at many mountain airports, especially when hangar space is unavailable. Passengers should be made aware that deicing often cannot be done until loaded for departure due to limited ramp space. It may also lengthen trip time.
Departing mountain airports can be as challenging as approach. Before leaving the ground, ensure you monitor braking action and calculate takeoff distances based on current conditions. And review climb gradients closely before placing your fuel order.
Even for powerful heavy business jets, meeting 2nd segment climb gradients can be challenging. “Most airplanes won’t go far if you have to meet an IMC departure’s climb gradient,” says Chilton.
The Gypsum 4 departure from EGE is an example of this, requiring 815 ft/nm or a climb gradient of almost 14%. Passengers should be advised well ahead of time that fuel stops may be required depending on departure weather.
An approved runway analysis program can improve departure performance from mountain airports significantly. Companies such as Jeppesen and APG can assist in calculating emergency single-engine departure procedures serial-number-specific to an individual aircraft, letting operators depart safely at higher takeoff weights referencing a simple online or paper chart.
In the event of an engine failure after V1, pilots would revert from TERPs-based DP to the single-engine procedure created by the runway analysis vendor. Flying the single-engine procedure exactly as published ensures terrain clearance for the given aircraft configuration, temperature and weight.
Runway analysis can offer significant safety and operational advantages when departing mountain airports, particularly for lackluster performers. Operators may already have access to runway analysis through a subscription service such as ARINC Direct, so it’s worth reviewing all existing resources.
In addition, Jeppesen offers limited-distribution tailored charting services. Airport qualification and familiarization charts are commonplace at airlines operating into mountain airports, and can be of great assistance to unfamiliar pilots by providing extra guidance, including photos taken on approach and enhanced textual and graphical representations of surrounding terrain.
Despite the challenges of mountain airport ops, proper planning and execution will result in a smooth and safe flight. As Todd Chilton says, “Never get your aircraft in a position you don’t know how to fly out of!”
Julian Tonsmeire lives and flies in the Rocky Mountains near Denver CO. A former turboprop pilot for a regional airline, Tonsmeire flies Citation 550s and 560s for a Denver-based Part 135 aircraft charter and management firm.
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