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Landing On A Contaminated Runway? Here's How To Know The Braking Conditions.


It's officially winter. With snow and ice covering runways around the country, it's a good time to review how runway condition codes work, and what you should do if you're landing on a contaminated runway.

Student And Instructor Slide Off The Runway

We pulled the following report from the NASA ASRS database. It's a good example of how, even with proper planning, you may find yourself in a situation where loss of control can sneak up on you...

Student and instructor were coming back from an instrument practice lesson. Approaching the airport and entering the downwind, the crew briefed the landing and made a special note for landing on the contaminated surface and what exactly could happen. It was made clear that the student would have control and the instructor would shadow along for safety. The approach, flare, and touchdown were all controlled and stable. A straight roll-out path remained for about 2-3 seconds after touchdown before the airplane veered left of centerline. The instructor took control to correct, and the roll-out path straightened back up. Airplane again started veering left no matter how much rudder and braking action was applied to the right. The aircraft left the runway surface into the snow at a very slow speed. No injuries were noted.

A thorough weather briefing, indicating runway MU values in the mid-high 20s was obtained prior to launching. ATIS was obtained prior to entering BTL airspace. At the time, runway conditions were thin dry snow over ice with MU values in the mid-20s. The MU values below 40 indicated less than ideal braking, but not impossible landing conditions. The crew believed the contaminated runway to be an acceptable risk. A better understanding of braking action reports, aircraft landing performance on, and different landing procedures for contaminated runways could be gathered and applied to conditions such as these to help determine the likelihood of conducting a safe flight.

How To Get Runway Condition Information

So how can you figure out what the runway conditions are like before you arrive at your destination?

When airports conduct a braking action test, they issue a NOTAM for the braking action. You can find the NOTAMs in ForeFlight, like the example below:


What Do The Numbers Mean?

The FAA previously used the "MU" scale to relay braking conditions. It was based on a 0 to 100 scale, with 0 being no braking, and 100 being perfect braking.

Today the FAA uses a more simple 0 to 6 scale. 0 is bad. 6 is good.

The numbers are issued for each third of the runway: touchdown, midpoint, and rollout. So when you're picking up ATIS, you're going to hear something like this: braking action 5/4/2.

Now for the terminology. When you used to talk to ATC, they referred to braking action as good, fair, poor, or nil. But "fair" has been tossed out the window, and you'll now hear "good, medium, poor, and nil", or a couple combinations of those words.


If You're Flying Into A Towered Airport...

When a braking action NOTAM is issued at a towered airport, they'll include it in ATIS. But keep in mind, even if a runway condition report is NOTAM'd for the airport, the tower is not required to give you a conditions report over the radio.

It's not because they don't want to be helpful, it's because they're often times very busy. If conditions are rapidly changing and the ATIS isn't representative of the true runway conditions, tower may give you updated runway information directly. But if you have a question about the runway condition after listening to ATIS, it's always best to ask.

If You're Flying Into A Non-Towered Airport...

We spoke to Kreg Anderson, who runs the non-towered Alexandria Municipal Airport in Minnesota (KAXN) to find out more. As a side note, Kreg started as the youngest airport director in the country at just 23 years old last year.

When you're flying into a non-towered airport, there may or may not be a NOTAM issued for runway conditions. And even if there is a NOTAM, it might not have the same FAA braking action codes due to a lack of airport operations personnel, equipment, or a general lack of aviation knowledge by city-appointed airport managers. This is why you'll sometimes find public-use, non-towered airports with snow or ice covered runways and no winter weather NOTAMs. On the other hand, some airport managers use a software program called the "Runway Condition Matrix" to determine braking reports, which is a great tool for smaller airports. When we're talking smaller general aviation airports, it all comes down to each airport's individual funding, staffing, and plowing equipment.

Preparing For Touchdown

When you touch down on a contaminated runway too fast, you can significantly increase your landing distance. Trying to compensate by over-braking only makes things worse.

On slick surfaces, your brakes are much less effective, and they can quickly get you in trouble. Initially after touchdown, use little to no brakes. Then, gently press them to feel their effectiveness. It's easy to get anxious and jam on the brakes, but that can lock up your wheels. And when that happens, your braking effectiveness decreases, and you can start sliding. The more gentle you are on the brakes, the easier it is to maintain directional control on the runway.

CDN Aviator

When All Else Fails: Go-Around

If you have enough runway, and braking/directional control is clearly a problem, going around even after touchdown may be an option.

During your go-around, adding power increases airflow over your tail, and you'll most likely have better directional control on the ground with the rudder (even considering left-turning tendencies). If you do go-around, lift off, and take time to think through your Plan-B. That might be making another attempt at the airport, but it might also mean flying to another airport with better runway conditions.


Preparing To Land In Less-Than-Ideal Conditions

Next time you fly, pay attention to the runway conditions. We're deep into the season for slick runways, and if you're not prepared, you can find yourself in a lot of trouble in almost no time at all.

Know the runway condition codes, give yourself enough plenty of runway to stop, be gentle on the brakes, and fly your airplane all the way to the taxi turnoff.

Tell us about your experience with slick runways in the comments below.

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