June 3, 2018
If you know what the Houston corridor is, just skip to the third paragraph. For those of you not yet informed, read on! Houston has two big airports, Intercontinental (IAH) and Hobby (HOU). One sits north of downtown, the other is south. Big airports mean big airspaces (Class B) that are primarily geared towards big (commercial) aircraft. Throwing smaller, slower GA (general aviation) aircraft into the mix is not a good idea and requires the tower to grant clearances and takes attention away from the airliners.
So GA aircraft would normally* stay away from the bigger airspaces by going around them. But because these two Class B airspaces are so big and, well, there are two of them covering the whole of Houston, going around is asking a lot! So, whether intentional or not, there is an east-west pathway — called a corridor — that is about halfway between Intercontinental and Hobby. Below is a “vector map” that shows what is considered to be the corridor. I used to hangar my aircraft west of Houston so, to go east, I’d have to go around the big airspace or fly through the corridor. Now that I’m on the east side of town, I have to fly the corridor to get to the west side.
Today I wanted to fly from my home airport (which is off that map and just to the right) to see, from the air, some property that is in the northwest area of Houston (just off the map, in the top left corner). To do that, it makes sense to “fly the corridor” rather than go around the big airspaces.
The Houston corridor is certainly convenient for east-west traffic, but there are restrictions. First, it’s only about 4 miles wide. Second, the ceiling (how high we’re allowed to fly before “breaking” into the big airspace) is only 2,000 vertical feet. But you don’t have 2,000 vertical feet to maneuver. You still have to maintain at least 500 feet (1000 feet is better) above the ground (and buildings), so at the very best, there is 1,500 feet of vertical space. But there’s also a new twist that’s been added in recent years… stadium TFRs! (TFR = Temporary Flight Restriction… basically, it’s off-limits to most aircraft.)
It’s hard to make out, but slightly to the left-of-center of the red area I marked as the corridor, and slightly below it you’ll see three gray circles.
Those represent airspaces that we are prohibited from entering when there is an event going on at the stadiums in their centers. The one at the top, as you can see, butts into the corridor for quite a ways. In fact, if that TFR is active, then aircraft will only have a 1-mile wide choke-point in the corridor. That’s 5,280 feet, and only half of that is your “lane,” or 2,640 feet. The corridor “box” available to a pilot suddenly got a lot smaller… 5 times smaller, in fact. What’s worse is that any aircraft coming from the opposite direction isn’t required to stay in their “lane.” You just have to hope they do. Aircraft moving across your vision are fairly easy to pick out, but one coming straight at you has very little relative motion (sometimes none) and so they are hard, if not impossible, to pick out. When traversing the corridor, I always have my landing lights on; I hope the other aircraft do, as well. Anything helps!
Those are the down-sides of flying the corridor but, on the up-side, saving time and fuel by cutting through Houston is only one advantage. The other is simply that you get a great view of downtown Houston! Without entering the big airport Class-B airspace, this is the closest you can get to downtown in a GA aircraft. Without a TFR active, you can get quite close, flying along the southern edge of the corridor, and can nab some great photos. On my flight on June 3rd, it was pretty hazy, but the photos are still fairly good.
I both love and dread the corridor. Does that make sense? Here is the track of our flight:
And a few pictures we took along the way:
(Note: these photos are not up to par. I accidentally took them 5-stops under-exposed, so they are heavily photoshopped to get them at all viewable. And, yes, I’m very sad about that.)
Also, I’ve mentioned flying the corridor in two other Texas-Flyer stories, “The Aventura’s Last Trip” (Sep 2005), and “Ferrying My New Plane, The Aventura” (Aug 2002).
I probably need to point out that from the FAAs perspective, there is nothing “official” about what I’ve described above as “The Corridor”. In other areas of the country with busy airspaces, there are official corridors, but this isn’t one of them. But I think you’d agree with me, looking at the sectional, that there is a de facto corridor between the two airports.
Radio communications through the corridor
As far as I know, there is no special radio frequency used when traversing the corridor…. but, man, I sure do wish there were! (If you know of any frequency that typically pilots use, please enter a comment at the bottom of this page and let me know!) You can bet I’d have my radio tuned to that frequency, if it existed. The general rule in aviation is to tune your radio to the closest airport.
As stated above, the closest two airports are IAH and HOU. Each has one or more frequencies for aircraft landing at the airport. As near as I can tell, they only share two frequencies: Unicom @ 122.950 and “Nearest ATC” @ 124.7. It’s unlikely that ATC would be concerned with aircraft in the corridor, but it might not be a bad idea to tune to 122.950 while traversing that airspace.
The other alternatives are the more ambiguous air-to-air frequency of 122.75, or 123.025 for helicopters. I say “ambiguous” because I know for a fact that both fixed-wing and helicopters (not to mention gyroplanes like mine) traverse the corridor, so which do I monitor? Also, many pilots use 123.45 for air-to-air. And it can get worse. Just do a web search for “air-to-air frequency” and you’ll see a lot of different frequencies in actual use, regardless of the official rule.
So, it sure would be nice if the FAA would assign a frequency for choke points like this. It would make passing through the corridor much safer and less nerve-wracking.
Update: ADS-B saves the day
As of January 2020, aircraft flying in the airspace “corridor” are required to have ADS-B/Out. (Yes, there are a few exceptions, but rare.) This — in theory — means that any aircraft in the area will be on your EFB navigation screen, assuming the aircraft has ADS-B/In and the proper avionics to display traffic. The other aircraft will certainly be on my EFB screen! This arguably reduces the importance of having common radio communications (but, in my opinion, there should still be an assigned frequency for corridor traffic).
Because of ADS-B, my “love and dread” has changed to “love and trepidation,” haha. It’s still a choke point so great care will always be needed.
* “Normally” is, of course, a specious term. Many GA aircraft fly in Class B, particularly if they are either flying an IFR flight plan, or on Flight Following. My friend, Chuck, sent me a track showing him going right over downtown Houston. ATC sent him that way when he was on Flight Following. Another example: I was flying near Destin, FL and on Flight Following, and the ATC controller sent me right over the main runway at Eglin Air Force Base! Yow! So, I’m really talking about GA aircraft that, for whatever reason, are not currently on IFR or Flight Following. And, to be really thorough, you don’t actually have to be on IFR or Flight Following to get Class B clearance. On a quiet day, they’d probably let you traverse the airspace, but if it’s busy, they can deny your clearance request.
– – – – – – – – – – –
If you are not viewing this post in a web browser, but would like to, click here.
To leave a comment, please scroll down to the bottom of this page. Thanks!
If you enjoyed this or any of my other blog entries, I suggest you subscribe to this blog so that you are automatically notified when I make a new entry. To subscribe, open this page in a web browser (if you haven’t already) and go to the top of this page, and look along the left side for the subscription field.