Braking action is 4/3/3. Do you know what that means?

On October 1st 2016, the FAA updated braking action reports. But there's some good news: you no longer need to memorize those confusing MU braking values. The update stemmed from a Southwest 737 accident in 2005. But it's not just that particular accident that caused the change.

Slip-Sliding Away

Every year, dozens of aircraft go sliding off of slick runways. Sometimes it's off the end of the runway, and sometimes it's off the side. And one factor the FAA has identified with countless accidents is confusion of what braking action reports actually mean, and how a pilot should use them.

That's especially true for us GA pilots. After all, those braking reports are meant for the airlines, right?

Actually, no. And you can read about it in landing accidents like this.

In the accident above, the pilot, who was flying a Cessna 310, received braking action readings for runway 4 at KPHN. The report was 35, 33, 36. But are those numbers bad, or good?

According to the AIM, MU (friction) values range from 0 to 100, with 100 being the best friction and braking action you can get. So how bad is 35? It's a third of the way up the scale.

When there are frozen contaminants on the runway, an MU value of 40 or less means that aircraft braking performance deteriorates, and directional control becomes less responsive.

So those braking values were bad.

In the accident, the pilot flew an ILS to runway 4, and broke out of the clouds at about 600 feet above the ground. On touchdown, the pilot stated "I don't believe there was ever any traction obtained, aircraft began a slide towards left side of runway."

The pilot said the left main gear hit a snow berm on the side of the runway, the nose swung around and also hit the berm, and the nose gear collapsed.

After the accident, the FBO owner came out to the runway in his pickup to help. As the pickup approached, it also had no braking action, and it slid into the same snow berm.

Obviously, the runway was too slick to safely operate on.

The New Reports

Because the MU numbers were often times confusing, they've been updated. And the FAA is issuing the new numbers on ATIS.

Now, there are only 7 numbers, ranging from 0 to 6. 0 is bad. 6 is good.

And 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.

What does that mean? If you look at the chart, it means the braking action for the runway is good at touchdown, good to medium at the midpoint, and medium to poor on the rollout.

So if you plan to use a lot of runway, or if you're fast and land long, which can be a problem when you're transitioning from an instrument approach to a landing, you're going to get worse and worse braking action the further you get down the runway.

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 here "good, medium, poor, and nil", or a couple combinations of those words.

What You'll Hear From ATIS And Tower

So what are you going to hear on ATIS? When airport operations conducts a braking action test, they issue a NOTAM for the braking action. And as soon as tower gets that, they'll include it on ATIS.

So when things get slick, expect to get a 3-digit braking action report like "4/3/3". Just remember that low numbers are bad, and high numbers are good.

And how about when you ask tower for a braking action report? If you're talking to them, they're not going to use the numbers. They'll stick with the words that describe the braking action: good, medium, poor, and nil.

Stopping On The Runway

When it comes to slick runways, you still need to make good decisions about whether or not you should be diverting.

But at least now the numbers used to report braking action are a little more straight forward. Instead of having to decipher a murky scale of 0 to 100, you only have to deal with 7 numbers. And if you ask us, a little simplification goes a long way.