Just like strong crosswinds or low clouds, you should have personal limitations for gust factor when you're approaching your destination.
Why Does Gust Factor Matter?
According to AOPA's Nall Report, nearly 40% of fixed-gear, single-engine accidents are on landing. And in the majority of those accidents, wind is a factor. We've all flown on days when the METAR says something like this:
KBJC 051953Z AUTO 29012G25KT 10SM FEW014 FEW090 06/M18 A2991 RMK AO2 SLP137 T00561183
Depending on what runways are available, how often you fly, and what kind of airplane you're in, 13 knots of gust isn't an unreasonable challenge. Every pilot will have a different comfort level when it comes to landing in gusty conditions.
Usually, the solution is to add half the gust factor to your final approach speed. Wind gusts can be variable and unpredictable, which are two things you never want to deal with when you're landing. When you fly on a gusty day, you know that your airspeed indicator can have some pretty wild fluctuations. If you're on speed or a little slow on final approach, a sudden loss in headwind from a gust could get you closer to stall speed that you'd like. And if you're like us, that's a pucker factor you'd rather not deal with.
When you're dealing with a gusty day, the FAA recommends that you add half the gust factor to your final approach speed.
How Must Gust Is Too Much?
Take a look at the weather report below.
Winds are from 320 degrees gusting from 34 knots to 56 knots... That's a gust spread of 22 knots. The single runway at the Kit Carson Airport (KITR) has a magnetic heading of 330 degrees, so the wind is more or less directly down the runway.
Would you land in a light piston engine airplane? The answer is, probably not. The liftoff speed in a C172 is usually about 48 knots, just 8 knots slower than the reported peak wind. In winds like these, you'd find it hard enough to control the airplane on the ground...much less in your flare just feet above the runway.
Even Jets Are Susceptible To Gusty Winds
Gusty winds aren't just a consideration for light airplanes. In 2008, a German A320 crew nearly lost control just feet above the ground during gusty winds. Here's a report from the Flight Safety Foundation...
During cruise, the flight crew received a Hamburg automatic terminal information system report of winds from 280 degrees at 23 kt, gusting to 37 kt. They planned for, and later received clearance for, an approach and landing on Runway 23, which is equipped with an instrument landing system (ILS) approach. When the crew reported that they were established on the ILS approach, the airport air traffic controller said that the wind was from 300 degrees at 33 knots, gusting to 47 knots.
A decision to go around would have been reasonable because the controller's report indicated that the winds exceeded the maximum demonstrated crosswind for landing, which was "33 knots, gusting up to 38 knots" and presented as an operating limitation in the A320 flight crew operating manual.
The captain asked ATC for the current "go-around rate," and the controller replied, "Fifty percent in the last 10 minutes." The controller offered to vector the aircraft for a localizer approach to Runway 33, but the captain replied that they would attempt to land on Runway 23 first.
The crew gained visual contact with the runway at the outer marker. The copilot, the pilot flying, disengaged the autopilot and autothrottles about 940 ft above the ground. The copilot used the wings-level, or crabbed, crosswind-correction technique until the aircraft crossed the runway threshold and then applied left rudder and right sidestick to decrab the aircraft, aligning the fuselage with the runway centerline while countering the right crosswind.
The A320 was in a 4-degree left bank when it touched down on the left main landing gear and bounced. Although the copilot applied full-right sidestick and right rudder, the aircraft unexpectedly rolled into a 23-degree left bank. It touched down on the left main landing gear again, striking the left wing tip on the runway, and bounced a second time.
The crew conducted a go-around and landed the aircraft without further incident on Runway 33. The left wing tip, the outboard leading-edge slat and slat rail guides were found to have been slightly damaged during the serious incident, the report said, but the ground contact was not detected by the flight crew.
How You Can Avoid A Similar Incident
The A320 crew justified their approach with the knowledge that 50% of the aircraft ahead of them landed successfully. The safer option would have been to take extra time to set up for the localizer approach to Runway 33, which was aligned much more into the wind.
While there's no perfect method for determining the maximum gust factor you should fly into, here are a few things you should take into consideration:
- Total Gust Factor
- Runway Condition
- Wind Direction vs. Runway Direction
- Runway Length and Width
- Recency of Experience
- Airplane Size
- Manufacturer Limitations
Most of all, avoid the temptation of using other pilots' success on landing as an indicator of safety.
Improve your landings for less than the cost of a flight lesson.
Do you have a perfect takeoff and landing every time? Neither do we. That's why we built our Mastering Takeoffs and Landings online course.
You'll learn strategies, tactics, and fundamental principles that you can use on your next flight, and just about any takeoff or landing scenario you'll experience as a pilot.
Plus, for less than the cost of a flight lesson, you get lifetime access to tools that increase your confidence and make your landings more consistent.
Ready to get started? Click here to purchase Mastering Takeoffs and Landings now.
$139.99
Become a better pilot.
Subscribe to the Boldmethod email and get real-world flying tips and information direct to your inbox, every week.
