Wednesday, May 06, 2009

Play Well With Others

I sometimes receive suggestions from readers about topics they'd like to see covered, which was the genesis for this post. If you have a suggestion, you can always email me at freightxdogxtalesxatxgmailzcom - just remove the Xs and replace the Z with a ".".

The FAA (and many instructors) do a good job of explaining what a complicated airspace system we have in the US, but we could do a better job of explaining why different classes of airspace exist. Pilots may be able to identify airspace classes on a chart, correctly describe the altitudes and lateral dimensions, and belch out the visibility and cloud clearance requirements by rote, but an understanding level of knowledge is more elusive. My concern today is simply Class E and G airspace, how VFR and IFR traffic can coexist at non-towered airports, how to make clear position reports whether you are VFR or IFR, and a common sense approach to resolving conflicts.

Why Class E?

All pilots need to remember that Class E airspace defines an area that may be shared by aircraft operating under instrument flight rules (IFR) and aircraft operating under visual flight rules (VFR) without an air traffic controller providing separation. What separates these aircraft is the see-and-avoid concept.

Class E airspace will surround non-towered airports with one or more instrument approach procedures and rural heliports that support emergency medical flight operations. Class E can also exist at airports that don't have continuous control tower operations: The airspace around the airport is Class D when the tower is open, but reverts to either Class E, Class G, or a combination of the two when the tower is closed. The best way to know is to check the Airport/Facility Directory entry for that airport.

IFR aircraft can operate in Class E in instrument meteorological conditions (IMC), in visual meteorological conditions (VMC), or they may be passing in and out of the clouds, so 14 CFR 91.155 requires pilots under VFR to comply with specific flight visibility and cloud clearance requirements. This helps ensure that VFR and IFR aircraft have a fighting chance to see and avoid one another since ATC isn't there to play referee and point out traffic.

Class E Depiction

Class E airspace is explicitly depicted in a variety of ways on VFR charts, but it can also be implied. A dotted magenta line encloses areas of Class E airspace starting at the surface and extending up to 18,000 feet. Surface Class E is usually defined around an airport where the FAA definitely doesn't want scud-running VFR aircraft who might pose a hazard to aircraft on an instrument approach.

The magenta vignette encloses areas where Class E starts at 700 feet above ground level (AGL) up to 18,000 feet. It is also found around non-towered airports that have instrument approach procedures or EMS heliports. The shape of the magenta vignette roughly describes the instrument approach final approach course, the missed approach segment, and/or the instrument departure path for that airport. Beneath the 700 foot floor of Class E airspace is Class G, or uncontrolled airspace.

I'm leaving out some of the other ways Class E airspace is depicted and remember that Class G (or uncontrolled) airspace exists underneath the magenta vignette. Adjacent to the magenta dotted line or vignette depiction, Class G exists from the surface up to 1200 feet above ground level and above 1200 feet, Class E up to 18,000 feet is implied. During the daytime, Class G has much laxer requirements for VFR visibility and cloud clearance than Class E and this will figure into the discussion a bit later.

Two Cars in Kansas

Let's get back to IFR and VFR traffic sharing the same airspace. Let's say you are a VFR pilot inbound to Ukiah, California from the Southeast. You were receiving flight following from Oakland Center when, about 12 miles out Oakland Center tells you "radar service terminated, squawk VFR, frequency change approved." You've already listened to the surface weather and know there is a 3,000 foot broken ceiling with 5 miles visibility in haze. The winds are 310 at 12 knots and runway 33 appears to be indicated. The sky is clear in your current location, so you begin a VFR descent to get under the cloud layer ahead. Next, you change frequencies and make your first announcement on the common traffic advisory frequency (CTAF):

Ukiah traffic, Mooney 123, 10 miles Southeast, 4000 feet and descending, planning right traffic runway 33, Ukiah.

Unbeknownst to you, there is a freight aircraft that is also inbound to Ukiah from the Northwest, operating under Part 135, and on an instrument flight plan. A bit later, Oakland Center clears the freight aircraft for an instrument approach and ends with:

Boxhauler 333, radar service terminated, change to advisory frequency approved, report cancellation of IFR on this frequency or with flight service, traffic is a VFR Mooney inbound from the Southeast, good day.

Since you've changed frequency, you don't hear that exchange. You've maneuvered your Mooney under the overcast, you have 5 miles visibility and are 500' below the clouds when you hear:

Ukiah traffic, Boxhauler 333, 8 miles Northwest, 3500, localizer 15 approach, Ukiah.

Get the Flick

You need to quickly assemble a mental picture of your situation: The freight aircraft is inbound to the same airport from the opposite direction, they may still be in the clouds, and they're planning to land on the runway opposite the one you have chosen. They just changed to the common traffic frequency so they did not hear your initial CTAF announcement. What's more, they probably have a faster groundspeed than you. Who has right-of-way? What should you say? How do you work out the opposite runway conflict?

The regulations (14 CFR 91.113) say that whoever gets to the airport first and it at a lower altitude in a position to land has the right of way. What's more that aircraft can land on any runway they want because all runways are active. This is why I recommend avoiding the commonly used phrase "the active" at non-towered airports - all the runways are potentially active.

Some pilots mights say Ukiah is an "uncontrolled airport," but that's a misnomer. It's certainly not in uncontrolled airspace since Class E extends all the way to the surface. More importantly, there is control at all non-towered airports. It's called self-control on the part of the pilots operating there, whether they are VFR or IFR. The keys to working out traffic pattern conflicts are clear communication, common sense, and courteous cooperation.

Where you At?

Clear communication using accepted phraseology is a good first step. Instrument-rated pilots, you can mention the instrument approach you are flying, but it won't be of any use to non-instrument-rated pilots or to pilots who are unfamiliar with the approaches to the airport. Reporting your position using approach fix names is just as meaningless. So whether VFR or IFR, keep it simple:
  • The airport name
  • Your aircraft model and tail number (or company and flight number)
  • Distance and cardinal direction from the airport
  • Your intentions.
Remember there could also be aircraft operating at a non-towered airport that don't have a radio or there could be an aircraft with a radio that has failed, so keep your eyes peeled for other traffic and expect the unexpected.

Speak Up

When you hear another aircraft make a CTAF announcement and realize there's potential conflict, that's your cue to say something. In our scenario, after you hear the freight aircraft make their announcement, you might say:

Ukiah traffic, Mooney 123 is 4 miles Southeast at 2500, planning right traffic, runway 33, looking for Boxhauler, Ukiah.

You can ask other aircraft if they are still in the clouds, what their ground speed is, or anything else that will provide you with the verbal equivalent of TCAS. If the other aircraft is still in IMC, you could ask them to say their intentions.
Ukiah traffic, Mooney 123, 3 mile forty-five, right traffic 33, the field is VFR, winds favoring runway 33, Boxhauler, say intentions, Ukiah.

Share Your Toys

Pilots at non-towered operations should have the same goal that air traffic controllers have: The safe and orderly flow of traffic. If another aircraft is faster and it's safe to do so, let them go first. Fly a wide downwind, slow down, or maneuver to give them time to land and clear the runway.

Instrument pilots, remember that you don't own the sky just because you are on an instrument flight plan or flying a practice approach. And remember too that not everyone understands instrument procedures and terms.

On the flips side, I've flown a lot of practice approaches with instrument students into non-towered airport and I can sympathize. When I hear someone inbound on an approach and they say they would like to circle in a non-VFR manner or do a straight-in approach, I try to accommodate their request if I can do so safely. Widening my traffic pattern or slowing down might cost me, what, two or three minutes of my time?

VFR pilots remember that you need to be at least 500 feet beneath the clouds in Class E airspace. Practicing touch-and-goes at a non-towered airport when the ceiling is low is risky business: Don't do it. Flying a non-standard 690 foot AGL traffic pattern so that you are just outside of Class E, technically VFR, and legal is also a poor choice.

Safe operations at non-towered airports depend on good radio technique, assembling a mental picture of what is happening, and being cooperative. Adhering to the rules also helps, but rules can't cover every eventuality. There's no replacement for courtesy and common sense. Being sharp and on-the-ball helps, too.


Anonymous said...

as usual, you post is great. When are you publishing your book? I will certainly buy a copy.
Have you tried to be a human factors consultant to GARMIN? You commens on the absolutly horrible user interfaces to GPS systems are right on the mark.

Ron said...

Yes, understanding the WHYs of airspace design is a very good idea. It also helps reinforce the numbers. For example, in my experience, knowing that the 250 knot speed restriction goes away above 10,000 feet helps explain why the cloud clearance and viz requirements also change at those altitudes. Faster airplanes need more time (and therefore distance) to see and been seen when they come out of clouds, haze, and other obscuring phenomenon.

I don't think poor radio phraseology is the major problem on the airwaves at non-towered airports. To my ears, it's mis-reporting of a pilot's position. Distances are often way off, and cardinal directions are frequently incorrect as well. The say right traffic when they mean left. Or runway 13 instead of 31.

The best phraseology in the world will not help in those instances.

The problem, of course, is the pilot's inability to visualize their position in relation to the airport. If they can keep the moving map in their noggin up to date, it makes life a lot easier. With the advent of actual moving maps, though, humans tend to let that kind of thing go.


Steve said...

Definitely a great post on an important topic.

To the above point about giving the wrong direction, I first have to say I know I'm as guilty as many in doing that at times. But the important thing is, whether you notice right away or a 30 seconds later, that you broadcast "correction, Cessna 12345 is six miles WEST inbound" and don't just assume it doesn't matter whether or not you correct yourself.

David Cheung said...

On a recent flight I had the experience of being in the pattern with someone who wasn't broadcasting their position and intentions regularly. I had to, on two occasions, ask for their present position and intentions. I was on an instrument approach in VMC to the runway in use. I tried to be as clear as possible to the other plane, but not knowing where he was presented a challenge.

Proper phraseology or not, situational awareness and timely communications are critical when there are multiple users at the airport.