Blown Away

Like Patrick Swayze's 1987 hit song "She's Like the Wind," there is no shortage of romantic analogies about what some simply see as an annoying, blustery condition—especially pilots! In fact, for aviators, the wind can be downright dangerous and even fatal if not effectively considered.

On February 21, 2022, a Hawker 800XP sustained significant damage during an accident in Aspen, Colorado. While none of the passengers or crew were injured and the accident remains under investigation, the preliminary report reveals some interesting facts surrounding the wind at that time.

During the preflight, the Terminal Aerodrome Forecast (TAF) predicted the wind to be from 210 degrees at 13 knots, gusting to 23 knots. Aspen was departing runway 33. Thirty minutes prior to departure, the ATIS reported the METAR winds at 170 degrees at 18 knots, gusting to 30 knots.

METAR provides the surface winds (to the nearest 10 degrees) over an average period of ten minutes. In this case, the ATIS wind report matched the METAR issued at 1753Z. ATIS broadcasts are generally only updated once an hour unless the wind direction changes by more than 30 degrees, or if the wind velocity changes by more than five knots over a five-minute period.

As the aircraft was cleared for takeoff, the tower reported winds from 160 degrees at 16 knots, gusting to 25 knots. When the tower reports the winds, it reflects a two-minute average wind (as compared to a ten-minute average from the METAR) and reflects the magnetic direction of the wind.

There was also a 4^th source of wind information provided to the crew as they were cleared for takeoff. The instantaneous wind report stated 180 degrees at 10 knots. With an overall variance in reports of 50 degrees and as much as 20 knots, there may be a lesson we can take away from this scenario.

There were at least three noticeably different wind reports provided, with two showing wind exceeding the maximum tailwind limitation for the airplane and the other just reaching the maximum limit. There's no way to definitively tell yet if winds were a looming cause in Aspen, but preventing accidents often means analyzing past data and determining where we might improve our own flight planning and execution. What should we do if we find ourselves in this situation?

First, knowing what each wind report means can be crucial to our planning. Instantaneous is measured in last three seconds and, in the case of Aspen, are measured from the northern end of the ramp near the threshold of Runway 15.

It is always good to cross check our data, but there is no way to tell if the crew in this situation did that by comparing the FMS depicted winds, which is a 30-second average. In dynamic wind conditions, getting your eyes on the action of the windsock is another great way to get a reliable idea of what you can expect.

At other airports, you may also utilize the automated surface observation system (ASOS) or the automated weather observation system (AWOS), both of which provide weather updates every minute.

There are many resources available to plan for wind, but we cannot discount the most important resource, which is simply the five senses of the pilot. Reports that are not current may not always reflect the changing conditions on the ground or in the air surrounding the airport.

Being alert, utilizing all resources at hand, understanding the information we receive, and respecting the limitations of our airframe can be the difference between a safe flight and a very, very bad day. Stay alert, stay safe, and don't let a lack of awareness blow you away.