TRSA Asks: Can You Handle The Truth?


The Oxcart English/Aviation Dictionary defines TRSA as: Terminally Redundant Suspicious Airspace. And here now to illustrate how TRSAs continue to evade mention in polite aviation salons, is a transcribed actual event that could’ve happened. Reader discretion is advised but not expected.

It began like any Tuesday, coming sharp on the heels of another Monday. A former student rode his eBike down the runway, fell off, leaned it against my hangar but delayed entering. Something was on his mind, but he was hesitant to speak. So, I called, “How was summer camp?” He’s a second lieutenant in the Air National Guard and a composite of six of my former students, wonderful people all. He mumbled in that adorable way butter-bar O-1s do, “Um, like, you know.”

He took a seat on an overturned bucket, and we stared at the airplane I was pretending to wax. I’ve pretended doing that for years with little progress. More importantly, as I searched for more importance, I could tell he burned to ask me something but was too embarrassed. Surrendering to that burning sensation, he mumbled, “Some of the captains at camp had, like, FAA manuals.” His voice broke. “With, like, graphics.”

Uh-oh. He was abusing “like.”

He continued. “And they, like, showed me.”

“Stop saying, ‘like’!” I imagined shouting.

His narrative turned accusatory: “You didn’t tell me everything I needed to know about … you know … airspace.” I reminded him that we’d discussed airspace ABCs in ground school—” But he interrupted, “I mean all of it, including the stuff no one talks about.”

I glanced at the portrait on the wall of former FAA Administrator Jane Garvey (not a pilot), and we exchanged knowing winks. It was time for The Talk. Time to teach without obfuscation the facts of flight, especially where airspaces come from. I repacked my pipe. I don’t smoke, but it imparted gravitas. “You see, Timmy—”

“It’s Justin.”

“When two airspace analysts really like each other, they …” And I retold the wondrous story about how airspace classes A through G—skip F because we don’t mention that crazy uncle in the attic—were created in the 1993 airspace reformation. And waving my pipe stem so the smoke formed uppercase letters in the air, I explained that prior to alphabet soup airspace, the sky was filled with unpronounceable creatures called ARSAs, TCAs and ATAs that are now Class C, B and ….  Justin interrupted, “But no one told me about TRSAs!”


“I didn’t think you were ready,” I whispered.

Flight instructors can be uncomfortable talking about TRSAs, because like unicorns or Bitcoin, they don’t exist, unless we believe they do. Thirty US airports believe they have TRSAs, and I’m guessing a like number of pilots understand them. TRSA really means Terminal Radar Service Area, and pilots flying through these spaces of air, surrounding designated terminal facilities (airports), can receive radar service. It’s possible to operate inside a TRSA without a transponder or talking to ATC, but that might be rude.

At first glance, a TRSA resembles Class C airspace, but it’s not. It’s nothing. Sectional charts (remember those?) depict this airspace hermaphrodite with black lines surrounding a core airport that has Class D airspace. I consider the lines more charcoal than black, but whatever. Class D airspace, depicted with dashed blue lines, has a control tower, and when it’s open, pilots shall establish two-way communication with the tower prior to entering the D airspace. Like this: “Kalamazoo tower, Citabria 26PK.” When tower replies, “Cessna 1508Y, Kalamazoo tower,” they’re talking to someone else, so be patient and try again. Once establishing two-way communication, you may enter D airspace but can’t land D airplane without a clearance. No transponder required, unless the D airspace happens to sit inside a Mode C ring surrounding more challenging Class B airspace. There are exceptions for aircraft “not originally certificated with an electrical system.” (FARs 91.215, 91.225)

When approaching a TRSA, associated with Class D airspace, VFR pilots should—not shall—contact approach control for radar service, which for VFR is mostly safety alerts, traffic advisories and sequencing, similar to Class C radar service. So, why the difference? And why have TRSAs at all?

No one knows.

Legend holds that TRSAs were still in gestation when the airspace ABCs were born. Their arrival eliminated old-school dominions, such as ARSAs. After alphabets filled the sky, someone noticed that TRSAs had hatched but lacked the Part 71 or 91 regulatory provenance conferred upon the newer designations. These orphaned TRSAs existed but didn’t, and those in charge didn’t know how to eliminate them. Still don’t.

Think of TRSAs as the ultralights of airspace. Part 103 sorta regulates ultralights. They’re not airplanes—mostly lawn chairs with wings—and because they’re not really airplanes anyone can attempt to fly one without a license. Crash, and you’re just another crumpled idiot on YouTube. Crash an ultralight inside a TRSA, and the FAA’s attorney, Tom Hagen, will conclude, “It’s like you never existed.”

Here’s what you need to know about TRSAs: Not much. Unless you’re on a check ride. After that, still not much. When encountering one (VFR; IFR pilots don’t need to know much airspace stuff), call approach control for radar service; there are few reasons to decline it. If flying an electrically deficient Aeronca Champ, skip approach and go straight to tower. They won’t understand anything you’re saying on your wheezy KX99 handheld, so watch for light signals.

When I finished explaining TRSAs to Justin, he seemed overwhelmed and yet disappointed to learn that there was much that primary instructors don’t teach. I was about to launch into my bilious fallback, “Learning is a lifelong adventure,” but instead, asked, “You okay?”

He shrugged, yes.


He sat thinking. Then, “So, does this mean I’m not ‘prohibited’ from entering Prohibited Areas?” A spreading grin implied forbidden intrigue with the prospect.

“Ask you mother,” I answered. “And quit using air quotes!” I resumed pretending to wax the airplane.

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  1. TRSAs gestated long before alphabet airspace. They were a non-entity when I started flying in 1979. Even then no one knew why they existed, but I always figured it was some combination of politics and the FAA modernizing by replacing 50 year old technology with 25 year old technology.

  2. Another good one, Paul. “So, does this mean I’m not ‘prohibited’ from entering Prohibited Areas?” – Spoken like a true middle schooler. Or second lieutenant, whichever.

  3. To see one on a chart check out Altus AFB (KLTS). It’s easy to see the chart markings because Altus is located in the middle of nowhere. According to the AIM:

    > TRSAs were never controlled airspace from a regulatory standpoint because the establishment of TRSAs was never subject to the rulemaking process; consequently, TRSAs are not contained in 14 CFR Part 71 nor are there any TRSA operating rules in 14 CFR Part 91.

    Altus is a good example of why TRSAs still exist. It requires a radar facility only because it has a lot of large aircraft flying around it all the time because it hosts the squadrons conducting initial training for the USAF’s KC-135, C-17, and C-5 aircraft. According to the AIM, TRSAs were originally intended to be converted to ARSAs, but “the ARSA requirements became relatively stringent and it was subsequently decided that TRSAs would have to meet ARSA criteria before they would be converted.” In other words, there’s no need to waste a lot of money converting a perfectly good TRSA to a Class C in a place like Altus.

    When I flew out of there it was manned exclusively by military controllers–I don’t know if that’s still the case.

  4. The introduction of class C airspace changed my life …. well …… a little. I used to fly at a gliderport (another good airport turned into a golf course) under the Manchester NH TRSA and everybody was happy. When the TRSA became class C, a lot of VFR pilots now HAD to talk to Manchester (now Boston) approach and didn’t wanna. So, instead, they flew under the class C and often right through our pattern.

  5. It would be helpful, if Avweb listed the actual TRSA’s left in the NAS. I think PSP still has a TRSA, but I bet pilots in Southern California airspace are unfamiliar with it.

    • Approach Control, City, State
      Montgomery Approach, Montgomery, Alabama
      Razorback Approach, Fort Smith, Arkansas
      Fairbanks Approach, Fairbanks, Alaska
      SoCal Approach, Palm Springs, California
      Augusta Approach, Augusta, Georgia
      Atlanta Approach, Macon, Georgia
      Atlanta Approach, Warner Robins, Georgia
      Rockford Approach, Rockford, Illinois
      Lake Charles Approach, Lake Charles, Louisiana
      Monroe Approach, Monroe, Louisiana
      Great Lakes Approach, Kalamazoo, Michigan
      Great Lakes Approach, Muskegon, Michigan
      Great Lakes Approach, Saginaw, Michigan
      Gulfport Approach, Gulfport, Mississippi
      Great Falls Approach, Great Falls, Montana
      Binghamton Approach, Binghamton, New York
      Elmira Approach, Elmira, New York
      Griffiss Approach, Rome, New York
      Wilmington Approach, Wilmington, North Carolina
      Fargo Approach, Fargo, North Dakota
      Youngstown Approach, Youngstown, Ohio
      Altus Approach, Altus, Oklahoma
      Erie Approach, Erie, Pennsylvania
      Harrisburg Approach, Harrisburg, Pennsylvania
      Harrisburg Approach, Harrisburg, Pennsylvania
      Wilkes-Barre Approach, Wilkes-Barre/Scranton, Pennsylvania
      Tri-City Approach, Bristol, Tennessee
      Houston Approach, Beaumont, Texas
      Longview Approach, Longview, Texas
      Huntington Approach, Huntington, West Virginia
      Guam Approach, Tamuninga, Guam

    • Anyone in Southern California who has recently received their Private certificate is familiar with PSP’s TRSA … it’s a favorite item on the oral exam.

  6. Small point about ultralights…
    There has long been a view, advanced by certain members of the aviation press, to the effect that ultralights are “vehicles” but not “aircraft” under the regulations.
    A literal reading of the regulations suggests they are both – although admittedly there’s enough ambiguity that a judge could rule the regulations intended to exclude them from being “aircraft”.
    The wording in 14 CFR 103 carefully sticks to “ultralight vehicle” and never once implies that these vehicles are “aircraft”; and in several places the wording seems a bit odd, if ultralight vehicles are “aircraft”.
    Still, the authors of Part 103 never actually said ultralight vehicles are NOT aircraft for the purposes of the regulations.
    14 CFR 1.1 defines both “aircraft” and “airplane”. Ultralight vehicles clearly meet the definition of “aircraft” and powered fixed-wing ultralight vehicles clearly meet the definition of “airplane”.
    Just sayin’.

  7. Paul, good essay. Responding to your comment on Sectional color codes, the TRSA boundary lines and associated characters are defined as “black” but in the printing process they are screened, for clarity, to about 80%, resulting in what looks like charcoal colored lines. Small detail, but the question came up several times through the years, and as a Flight Instructor at Palm Springs, I looked into this as I needed an explanation to flabbergast students.
    KPSP is a part time Class D airport with a part time TRSA. The PSP TRSA was a consequence of a fatal accident. Uproar led to a radar facility that was subsequently upgraded to an ASR-9 then to an ASR-11 radar, now connected to SOCAL at Miramar, some 66 nm SW. No more Up/Down ATC at KPSP.
    KPSP is very close to high terrain with an interesting mix of traffic, both fast and slow movers, compounded by traffic from two other airports, KUDD and KTRM. Thus, the PSP TRSA is in the books as somewhat of a small hub serving all three. It was a good thing when first implemented and I think that it continues to serve well. I instructed there for over twenty years, having enjoyed the wild ass rides due to winds and thermals. KPSP was one of my landings during my first solo cross-country flight back in 1967 and I was fairly impressed while going through the Banning Pass then on the approach to the landing. That Up/Down part remains.

      • Thanks. A half-million years ago, I was a controller at MRY tower/approach. I believe we had an ARSA at the time. Flew Banner pass some years later in my Marquart biplane from Iowa via PSP to VNY with many fuel stops. Smooth day, good ride, until I got totally lost in the Socal area and pissed off every controller en route.

  8. I think TRSA’s first came into being in the late 60’s. If I remember correctly, it was also referred to as ‘Stage III’ radar service. The private pilots I knew took umbrage at being being asked if Stage III radar service was requested. ‘Negative Stage III’ was always their reply. ‘I ain’t lettin’ departure control tell me which way to fly. Hell no.’ Back when I learned to fly (the good ol’ days) at the Raleigh Muni airport (uncontrolled), there was approach/departure control and a tower at RDU airport 15 miles to the west, but vfr aircraft would usually just call tower approaching about 5 miles out. My airplane didn’t even have a transponder. Prior to my private pilot check, vfr flight following was not a thing, and I flew into a tower controlled airport (RDU) only 1 time.

  9. Paul Berge as ever. I would bet he even remembers the hand prop job I administered at CNH
    some time past in the days of antiquity. I even have, somewhere, a signed copy of “Bootleg Skies” to, like kinda, prove that we had a connection.

    Frank L.

    • Frank, I do recall that late afternoon “quick turn around” in my Champ, cruising toward northern Vermont’s Caledonia County Airport (KCDA). That was a beautiful trip and a long time ago. I still have your Franks Flight Service business card–and refrigerator magnet–on my hangar wall (6Z6). Gotta get me a copy of that there Bootleg book….

  10. TRSAs were the little brother to TCAs. Terminal Control Areas were regulatory with their very own weather minimums and rules (similar to Class B and at those very same airfields). TRSAs and TCAs were identical except that TRSAs were unregulated. They were there to provide guidance mostly to IFR traffic and radar service to anyone who asked. Today if you’re filed IFR you probably won’t notice any difference from Class C airspace but you don’t have to talk with them if you don’t want to if you’re VFR.

  11. As described in 14 CFR 91.225, ADS-B Out performance is required to operate in Class A, B, and C airspace. Above the ceiling and within the lateral boundaries of a Class B or Class C airspace area upward to 10,000 feet MSL. Note that ADS-B is not required in Class D airspace, or under a Class B or Class C airspace shelf, unless it lies within a Mode C veil, nor within TRSAs.