Sunday, July 17, 2022

Cessna T337G Super Skymaster, N337KN: Fatal accident occurred July 17, 2022 in Gold Hill, Boulder County, Colorado

Ian Kirby, Sandra Kirby and Amanda Kirby

Benjamin Thompson

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.
Investigator In Charge (IIC): Cawthra, Joshua

The National Transportation Safety Board traveled to the scene of this accident.

Additional Participating Entities:
Federal Aviation Administration / Flight Standards District Office; Denver, Colorado
Textron Aviation; Wichita, Kansas

VX Aviation LLC 

Location: Gold Hill, Colorado
Accident Number: WPR22FA256
Date and Time: July 17, 2022, 09:38 Local 
Registration: N337KN
Aircraft: Cessna T337G
Injuries: 4 Fatal
Flight Conducted Under: Part 91: General aviation - Aerial observation

On July 17, 2022, about 0938 mountain daylight time, a Cessna T337G, N337KN, was destroyed when it was involved in an accident near Gold Hill, Colorado. The pilot and 3 passengers were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 aerial observation flight.

Recorded Automatic Dependent Surveillance Broadcast (ADS-B) data showed the airplane departed from Rock Mountain Metro Airport (BJC), Broomfield, Colorado, and proceeded along a westerly course for about 4 minutes, before a right turn to a north-westerly heading was initiated.

As shown in Figure 1, the ADS-B data showed at 0938:37 the airplane had ascended to an altitude of 9,500 ft mean sea level (msl). The tracking then showed the airplane making a descending left turn to an altitude of 8,600 ft msl by 0938:46. The airplane then initiated a right turn. The last recorded ADS-B target at 0938:47 at an altitude of 8,400 ft msl was located about 579 ft northeast of the accident site. 

Multiple witnesses located near the accident site observed the airplane fly over their position, the right-wing rose abruptly and the airplane pitched nose down and “corkscrewed out of view” in a counterclockwise rotation.

The airplane impacted mountainous terrain on a heading of about 283°. The general accident area consisted of trees that were about 70 to 100 ft tall. The first identified point of contact was a cluster of 3 trees, that were broken about 17 to 20 ft above the ground.

The airplane came to rest mostly upright on a heading of about 091°. All major structural components of the airplane were located within about a 30 ft by 40 ft area. The area surrounding the wreckage was fire damaged.

The wreckage was recovered to a secure location for further examination.

Aircraft and Owner/Operator Information

Aircraft Make: Cessna 
Registration: N337KN
Model/Series: T337G 
Aircraft Category: Airplane
Amateur Built:
Operating Certificate(s) Held: None
Operator Designator Code:

Meteorological Information and Flight Plan

Conditions at Accident Site: VMC 
Condition of Light: Day
Observation Facility, Elevation: KBDU, 5289 ft msl 
Observation Time: 09:35 Local
Distance from Accident Site: 10 Nautical Miles
Temperature/Dew Point: 27°C /10°C
Lowest Cloud Condition: Clear
Wind Speed/Gusts, Direction: / ,
Lowest Ceiling: None 
Visibility: 10 miles
Altimeter Setting: 30.22 inches Hg 
Type of Flight Plan Filed: None
Departure Point: Broomfield, CO (BJC)
Destination: Gold Hill, CO

Wreckage and Impact Information

Crew Injuries: 1 Fatal
Aircraft Damage: Destroyed
Passenger Injuries: 3 Fatal
Aircraft Fire: On-ground
Ground Injuries: 
Aircraft Explosion: None
Total Injuries: 4 Fatal 
Latitude, Longitude: 40.068681,-105.42929

Aircraft crashed under unknown circumstances. 

Date: 17-JUL-22
Time: 19:47:00Z
Regis#: N337KN
Aircraft Make: CESSNA
Aircraft Model: P337
Event Type: ACCIDENT
Highest Injury: FATAL
Total Fatal: 4
Flight Crew: 1 Fatal 
Pax: 3 Fatal 
Activity: UNKNOWN
Flight Phase: UNKNOWN (UNK)
Operation: 135
Aircraft Missing: No

Those who may have information that might be relevant to the National Transportation Safety Board (NTSB) investigation may contact them by email, and any friends and family who want to contact investigators about the accident should email You can also call the NTSB Response Operations Center at 844-373-9922 or 202-314-6290. 

The coroner in Boulder County has yet to identify the remains of four people on board a Cessna T337G Super Skymaster that went down in Lefthand Canyon Sunday morning. The plane was operated by Bluebird Aviation said the NTSB. The company based out of Rocky Mountain Metropolitan Airport in Broomfield flew for only about ten minutes before going down on a steep incline and starting a fire.

"Everything's going to be looked at, I mean the toxicology reports are going to be looked at. The maintenance of the aircraft and whether the engines were performing properly. Weather, performance, maintenance, human factors, they're all going to be looked at, to see if one was a major contributing factor, or if all were a contributing factor," explained Kevin Kuhlmann, chair of the Aviation and Aerospace Science department at Metropolitan State University of Denver.

Flight data shows the plane was cruising at over 100 miles an hour shortly after takeoff until it made a turn in the canyon after going over Gold Hill. Then the airspeed fell into the 70s as the plane turned. Then it turned again while losing altitude and crashed.

The company flew sightseeing tours, carrying passengers often over the foothills. Its state registration shows Benjamin Thompson of Louisville as registrant and director of operations. The Bluebird Aviation website, now down, showed a picture of pilot Benjamin Thompson. FAA records show the plane's registration lapsed at the end of April. The FAA said the registration would be part of the investigation.

But the airport is not under any requirement to check a plane's registration prior to departure or landing. 

"The person flying the aircraft might not necessarily be the person that owns the aircraft. But it is still the responsibility of the pilot when he gets in that aircraft to make sure that the registration is current. Because that is one thing that is required to be on board and visible. It all boils down to the pilot," said Justin Parrow, longtime owner of an aircraft maintenance company based at the airport, which he recently sold. 

The registration is not dependent on the airworthiness of the aircraft. 

"No it's completely separate," said Parrow.

 Required logs keep track of items like an aircraft's maintenance.

"Every year an aircraft has to go through the annual inspection process," explained Parrow. 

"You do a physical inspection on the engine, the airframe, that landing gear. Make sure all bearings are within tolerances, the engines are the compressions on the engines are good," he said. 

"Same thing with the airframe itself. You take out all the seats, open up the floors, and do a real good inspection on all that," said Parrow. 

But there's no indication yet that the aircraft's condition was to blame, or that there was any failure to do the annual maintenance.

"The rising of the terrain in the performance of the aircraft don't always match up and especially when you're talking about fixed wing single engine multi-engine aircraft small aircraft," said Kuhlmann, noting that less experienced pilots might have difficulty. Colorado's mountains hold special challenges with the thin air at altitude. 

"You certainly can get weather conditions that are different and influenced by the rising and descending terrain, so you do get updrafts and downdrafts," said Kuhlmann. 

Planes have gone down when pilots get into canyons from which there is no escape, but over altitude, they cannot achieve. 

"The pilot may have tried to climb, and when the airspeed gets below a certain level the wing can stall, which is not to be confused with engines stopping," said Kuhlmann.  

A stall in an aircraft is a matter of aerodynamics. There isn't enough lift.  All are only potential, noted Kuhlmann, in a process that could take a long time. None of the potentials are to blame until an investigation is complete. 

Family members say a mother and two children from Port Allen, Louisiana are three of the apparent victims in a plane crash in Lefthand Canyon west of Boulder on July 17. The plane's pilot also died. 

The Boulder County Coroner is yet to identify the victims who were on board a  Cessna T337G Super Skymaster when it went down about 10 minutes after the sightseeing plane ride began at Rocky Mountain Metropolitan Airport.  A fire followed the crash.

"Crying my eyes, my heart out," said the children's father Joe Kirby. "Very little sleep."

The sheriff came knocking on Wednesday night to let them know. His ex-wife, 48-year-old Sandra, and his two children, 17-year-old Ian Kirby and 13-year-old Amanda Kirby, were believed to be on board.

The children visited his home for a time a few weeks ago.

"Ian just got his learner's permit this year and was driving. When he came out to visit with me, weekends I had him, I would take him out and drive and get him a little bit further along so where he could get his driver's license." 

Amanda was a sweet girl going into the 8th grade. She hoped to be playing clarinet this year. Ian played trumpet in the band. He was headed into his senior year in high school.

"Very good kids. Lovable, go out of their way to help anybody as much as they can." They loved each other said their father. "I looked out for both of them as much as I could."

Joe knew his ex-wife and the children were headed out west to Utah and Colorado. He didn't know they'd be taking a sightseeing plane trip. The NTSB says the plane was being flown by Bluebird Aviation. The pilot has yet to be identified. 

The investigation is just getting underway. There's no indication what may have caused the plane to go down. Flight data shows it slowed as it turned in Lefthand Canyon, then turned back and crashed. 

Joe isn't placing blame.

 "I would just like to know what happened and just go from there." He had words of thanks to emergency workers. "We appreciate all the responders that had come out take care of my family, and the pilot to make sure that they were taken care of the best way that they could."

His shock and heartbreak are just beginning. "Very proud of them. As I said they loved everybody that they came in contact with. I don't think they hated anybody."

BOULDER COUNTY, Colorado — The death toll has been raised to four people after a plane crash sparked a wildfire in Boulder County Sunday morning, according to the FAA. 

On Sunday, the Boulder County Sheriff’s Office said one fatality was confirmed but more were possible.

FlightAware, an airplane tracking program, shows that the plane took off from Rocky Mountain Metropolitan Airport and was in the air for just 10 minutes.

BCSO spokesperson Carrie Haverfield said recovery efforts for the victims were taking place Monday afternoon. The recovery efforts for the remains concluded at 3 p.m. on Monday.

Due to the significant damage the plane received, Haverfield said it has taken some time for investigators to locate and recover the remains of each victim. Additionally, she mentioned that detectives need to use utility terrain vehicles to access the area due to the rugged terrain which has played a role in the length of the investigation.

NTSB Spokesperson Peter Knudson said they arrived on the scene Monday to investigate the crash.

NTSB’s flight track data indicates that the airplane made a descending left turn which continued to the site of the accident. NTSB also said the significant fire post-crash consumed quite a bit of the wreckage.

Officials said it was too hot to complete the full investigation on Sunday due to the fire.

Boulder County Coroner’s Office has not confirmed the identity of those killed. The National Transportation Safety Board and FAA will investigate the cause of the crash.

FOX31 chased down the plane’s history and learned at some point the plane was used by BlueBird Aviation, a company that offers scenic air tours.

FlightAware shows the plane was in the air for just 10 minutes before it went down and the same plane flew roughly the same loop at least eight other times this month and dozens of times this year.  

A TripAdvisor website said the air tours fly over Denver, Boulder, and the Mountains. Mountain Tours are $275 per person and date night tours with complimentary champagne and video are $310.

BlueBird Aviation has not returned our request for comment but it remains unclear if the three passengers on board were part of a paid tour or not. 

Wendy Maier lives full-time in Larkspur but her husband’s family built the cabin in a remote part of Boulder County in the 60s.

“That’s the thing that we have always dealt with up there is the communication,” said Wendy Maier. “We do go there to get away from everything.”  

She mentioned that because it is such a wooded area, wildfires are always a concern, on Sunday when they received a notification about a wildfire near Maier family’s cabin it reminded them of the fires that came 1300 feet from their property line last summer.

“We got a phone call. And it was the reverse 911 call saying you need to prepare to evacuate. It was from Boulder County,” Maier said. “We literally said a couple of choice words. And then we said Oh, no, not again.” 

What she learned later, was the fire was caused by a plane crash.  

“Oh, it was it was really saddening to hear that it was a plane crash because that just multiplies the concerns. You know, you’re concerned about the people in the crash. Did it hit anybody that had any homes?” Maier said.  “It’s just really scary.” 


  1. This airplane seems to have regularly flown the same counter-clockwise route. They generally seem to cross the Ward / Gold Hill area about 1000ft higher and cruise-climb much faster. 90 kts and 350 fpm at 9500ft? That's more like 172 performance than T(P)337 performance. Something was wrong and they knew it before even getting over the mountains, why didn't they turn around?

    1. Furthermore, it looks like the autopilot was engaged and in VS mode. Ruler-straight heading and climb profile with degrading airspeed. Maybe trying to free up some workload while troubleshooting the performance issue?

    2. My friend was the pilot and I am trying to find information about the crash, can you share where you are finding this information?

    3. So horribly sorry for the loss of your friend and under this tragic conditions. The news has been slim and I am right here at Ground Zero and just hearing the confirmation of 4 souls on board. Kathryn's Report is a quick source and once the NTSB posts, you'll find information here:

    4. "cruise-climb much faster. 90 kts and 350 fpm at 9500ft? That's more like 172 performance than T(P)337 performance"

      If you are getting that info from ADSBx or Flightaware, both reference ground speed not airspeed just FYI.

    5. Yes, but it was a pretty calm morning so GS and TAS are going to be similar. Certainly not going to make up for much of a 30 kt discrepancy. And climb rate doesn’t matter what the wind is doing. They were obviously scratching for climb rate even in the class D surface area, why continue?

    6. Performance is diminished at 10k ft. Density Altitude has the greatest impact on performance.

    7. The last track was at 9500feet on a heading of 322 degrees at 11:38:18 167 fpm climb then at 11:38:36 a new heading of 245 degrees at 108kts with no altitude increase or decrease. The aircraft sounds like it could not climb anymore and got into a stall spin to the left.

  2. Aircraft was part of a flightseeing tour agency. Explains the repetitive ground track.

    1. Bluebird Aviation. Google search brings up picture of that plane. Their website is currently listed as "private".

    2. Instagram and Facebook taken down as well. Owner of company is an attorney.

    3. has some remnants from captures. Not many of the website's pages are saved but two nice inflight Skymaster pix show up there in the photo gallery:

      Skymaster among the mountains:

      Skymaster among snowy mountains:

    4. Two more Skymaster in flight photos:


  4. Based on climb rate and groundspeed in the ADS-B data, this looks like a failed engine, especially when compared to previous flights that followed the same path. Whatever the cause, this is really sad.

  5. Updated to 4 fatalities

  6. I saw this plane as I was riding my bike up to Gold Hill and was approaching town from 4-mile. I immediately heard the noise and at first thought it was a helicopter in trouble but then looked up and saw the plane. The engine was sputtering and my first thought was that it was out of fuel. It was fighting to stay in the air and then I saw it dive, then saw the smoke......hard to watch....really sad.

    1. ^^Your information if true is valuable to the investigation team (it's strictly voluntary but doing the right thing is highly suggested). Here's the directive from the NTSB if you witness a crash:

      "If you witnessed an aircraft accident and would like to provide the NTSB with a statement of your observations, please prepare a statement and email it to Please be sure to include a telephone number so that an investigator can contact you if necessary."

  7. Don't know what the density altitude was at the time but I do know a 337 has one of the best single-engine numbers for a light twin. It actually runs better on rear engine than it does the front. It is approved for single engine takeoff on the front engine. The report of sounds of the engine sputtering is troubling in that it sounds like both engines were starved of fuel. If only one engine was out the other would most probably be at max sustained power. Way too early to speculated. It is a terrific aircraft.

    1. Sorry, but the T337G and/or P337 IS NOT approved for single engine takeoff.

    2. Many years flying from kbjc. Local CFI. Accident indicates stall in a turn. This happens too often on high density altitude days. Bonanza in a canyon
      Near Telluride last year. You CANNOT make a level or climbing steep turn at slow airspeed. Stall speed increases with bank angle and more space and ground speed is required to maintain necessary INDICATED airspeed.. . Tragic.

  8. 1000' above the terrain below, 11 nm from Boulder, 4000' above Boulder. What level of insanity does it take to keep climbing towards the continental divide when you have tons of room to make a descending right turn? They could have easily glided to Boulder, probably even Erie.

    1. Probably not glide to boulder but yeah, not the right direction to be going.

    2. Sorry, I meant "sputter glide" with minimal power. Condolences to all involved, so sad.

  9. Whatever the mechanical was that caused the loss of power, it is obvious from the flight data that the PIC was aware of the issue from shortly after takeoff at the latest. Continuing the planned flight into steep terrain was borderline suicidal. I am not surprised that the owners of Bluebird have pulled every shred of internet presence down. The incompetence is staggering.

  10. The pilot was my good friend! I went to flight school with his father 35 years ago. If the person that flew to my house with him in the carbon Cubs on Saturday before the crash would find some way to contact me. You know my first name and you know where I live so easy to find. Last name Denny. Thanks

    1. We are trying to contact you.having trouble finding an email. Going through hangar contacts to get a phone number.

  11. The victims have been identified. Absolutely tragic.

  12. There have been enough one engine out Skymaster crashes to suggest the platform is not the best equipment for low AGL tour flying.

  13. The p-337 is a heavy bird. Ad four people and fuel with high density alt. and the performance will be marginal at best. Lose an engine and she won't stay above terrain.

    1. A one engine lead weight in soggy air. Amen.

    2. It was a very hot day, too.

    3. I own a P model 337. At gross it will hang in there at about 16,000 on one engine. The trouble is if it's hot and high the rear engine at slower climb speeds almost immediately starts to run high temps. Still hard to believe this crash scenario. Almost like he thought he could complete the mission on one engine or get the other one going again. I once flew a 337 over 300 miles over the jungle on the rear engine at night in bad weather

  14. As a candidate for an air taxi certificate I am puzzled... the stringent regs for air taxi (PART 135) require not only takeoff + performance data calculations, but a multi engine will be subjected to more rigorous check.
    It takes years to get such a certificate and it is worth gold if properly used. You can basically "hold out" ie advertize to anyone and charge anything you want for air rides and also do it from A to B plus not be limited by a 25 mi radius like in the case of Part 91 air tours or limited to 1-2 commercial clients.
    There is a reason not everyone gets to be a Uber driver of the sky and it's all about standards of safety... Air taxis are supposed to have safety mechanisms in place orders of magnitude more than General Aviation.
    The pilot is subjected to 135.293/299 checkrides and line checks yearly. Also a yearly class 2 medical. Everything needs to be document and the weight and balance data also kept.
    As far as the plane being out of fuel this would be an egregious violation of the regs.
    Unless misfueled with JET-A but generally trouble start on takeoff not in cruise.
    I suspect a drift and gradual carelessness, and it might the owner/operator not the pilot, especially if maintenance items were missed.
    If a lawyer the owner will certainly need to answer some questions but seems his instinct already is at work and he will use every trick in the book to just release the barest of bare minimum legal info.
    Some rules/maintenance items were certainly ignored or complacency set it, for an accident that bad to happen to an air taxi...

    1. Neither N337KN or the C182 (N2882Y) the business used for tours are listed in the FAA's Part 135 Aircraft Listing database, which shows a most recent update date of 7/1/2022 when downloaded and searched at the time of this reply post.

    2. ASIAS entry shows part 135 up in the posting info, but looking at where the tour route made it's turn at the farthest northwest distance on July 7, 8, 9 and 10 suggests that the pilot was aware of the 25-statute mile radius limit of part 91.147:

      Step the history forward thru July 10 and the turn location at the northwest is consistent. Measuring from 17:29:43Z location in that turn on 7 July of 40.154, -105.606 maps at 30 statute miles from Rocky Mountain Regional Airport:

      Map=pinned location in the NW example turn:

      The Skymaster was 19 statute miles from Rocky Mountain Regional Airport at the time of the crash.

    3. confirmed. Rocky Mountain Regional Airport KBJC to 40.154, -105.606 is SE @ 31 mi. per,+-105.606-KBJC&PC=%23ff0000&RC=%23000080&DU=mi&SU=kts

    4. Then how come the NTSB report seems to indicate 135? Either way 147 would be more relaxed but still as any commercial ops required to do more due diligence regarding all factors, Also a briefing on takeoff of what to do in an emergency.
      And frankly for pax's sake why so many operators choose to not try a 135? Like the instrument rating I believe it is also something that can save one's life. I don't care if you're a piper archer or C172 driver... just do through the steps and start incorporating the safety needed to hold out into your everyday ops.
      It is required? no? but like all things in aviation, you either keep on learning and imrpoving or you become... dangerous.

    5. Part 91 tour operation within the 25 mile limitation is a regulatory carve-out to reduce business expense and compliance complexity from what a 135 operation is subjected to. Hard to compete on price in a tourist zone as a 135 if the 91 operators are snapping up your customers on lower pricing.

  15. 210 hp of one engine dont sustain that twin at almost 10k density alt. You will stall trying to keep alt. Push nose down and accept to land it instead. Be a man. He stalled it in panic. I used to drive one with the Robertson Stall Kit. One engine down, you go down unless low temp and low weight too. What a shame.

    1. That is funny. I used to own that exact airplane. The single engine service ceiling is 18,700 feet on a single engine at gross weight. The horsepower is 225 hp and it is turbo-charged. It is great how much good information there is in these replies!