I thought there was a tacit contract among all professional aircrews that can be summed up briefly as, “I agree not to kill you.” Expanded, this contract reads:

“I agree that during the approach and landing phase, we will err on the side of caution and if either pilot becomes uncomfortable to the point of calling for a go around, the other pilot will immediately go around.  We will discuss the reasons for the go around after we safely land. The only exception can be if fuel or other conditions make a second approach impossible. Further, if the call for a go around proves unnecessary, there will be no hard feelings; we will learn from the event and press on.”

I say I thought that this contract is tacit—that is to say “understood” without having to be said before hand—but now I am not so sure.  Consider the loss of control of a Challenger 605 at Truckee Tahoe Airport (KTRK), California, on July 26, 2021.  

The pilot in command (PIC) was also the pilot flying (PF) and had 235 hours in Challengers, most of that in the older Challenger 601. The second in command (SIC) was the pilot monitoring (PM), was a contract pilot and was highly experienced with well over 4,000 hours in Challengers. Both pilots and four passengers were killed in the crash.
 
The PF shot the KTRK RNAV (GPS) 20, attempted to circle to Runway 11 and lost control of the aircraft. While much of the focus has been on the weather, which was adequate, and the fact the aircraft maneuvered too close to the landing runway to successfully circle, all of that misses the critical point. To really understand the tragedy of this accident, one need only read the last 60 sec. of the cockpit voice recorder (CVR) transcript:

13:17:12.6 (PM) we don't wanna be on the news.
13:17:14.8 (PM) autothrottles have it.
13:17:17.8 (PM) you are looking very good my friend.
13:17:24.1 (PM) nice and relaxed...bring that turn around.
13:17:24.3 (cockpit microphone) sound similar to increase in engine rpm
13:17:27.5 (PM) perfect.
13:17:30.2 (PM) it's okay...you got plenty of time.
13:17:33.6 (PM) let it keep comin' down though.
13:17:41.4 (cockpit microphone) one thousand. [electronic voice]
13:17:42.7 (PM) did you? oh you turned the throttles off...
13:17:43.5 (cockpit microphone) [sound similar to altitude alert]
13:17:44.4 (PF) yes.
13:17:44.6 (PM) shoot (expletive)
13:17:46.4 (PM) let me see the airplane for a second.
13:17:51.6 (cockpit microphone) sound similar to decreasing engine rpm
13:17:54.7 (PM) we're gonna go through it and come back okay?
13:17:56.8 (PF) okayyy …
13:18:00.4 (PF) It's here. [exclamation]
13:18:01.4 (PM) yes yes it's here but we are very high.
13:18:03.6 (cockpit microphone) sink rate. [electronic voice]
13:18:04.2 (cockpit microphone) sounds similar to stick shaker activation
13:18:04.2 (PF) what are you doing?
13:18:04.2 (cockpit microphone) pull up. [electronic voice]
13:18:04.5 (PM) ‘kay.
13:18:04.8 (PF) (unintelligible word)
13:18:04.9 (cockpit microphone) warbler sound consistent with stall warning
13:18:05.0 (PM) no no no.
13:18:06.2 (PM) let-
13:18:06.5 (PF) what are you doing?
13:18:06.6 (cockpit microphone) pull up. [electronic voice]
13:18:06.6 (PM) let me have the airplane.
13:18:07.3 (PM) let me have the airplane.
13:18:07.9 (cockpit microphone) sounds similar to stick shaker activation
13:18:07.9 (cockpit microphone) warbler sound consistent with stall warning, continues throughout the end of the recording
13:18:08.0 (cockpit microphone) pull up. [electronic voice]
13:18:08.6 (PM) let me have the airplane.
13:18:09.4 (cockpit microphone) pull up. [electronic voice]
13:18:09.7 (PF) oh. [exclamation]
13:18:10.0 (PM) oh (expletive)
13:18:10.8 (PF or PM) (expletive)
13:18:11.0 (cockpit microphone) pull— [electronic voice]
13:18:11.3 (cockpit microphone) (sounds consistent with impact)
13:18:12.2 End of recording

The NTSB investigation continues but the accident docket already has a lot of important information, including the CVR transcript. If you’ve never explored an accident docket before, this one will be a valuable, if sobering, introduction. Go to www.ntsb.gov, select Investigations, Investigations Dockets, and enter the search criteria. You could enter the accident date and other particulars, but in this case, you can simply type in the NTSB Accident ID Number, WPR21FA286. As the investigation continues the docket will grow; as of this writing there were 35 items.

This docket not only makes for a great Crew Resource Management (CRM) case study, it provides several lessons about aerodynamics and aircraft stall characteristics. If you are a Challenger pilot, you will learn more about your aircraft’s low-speed flying characteristics than you’ve ever learned during initial or recurrent training.

It will be natural for most pilots to say they would not have put their aircraft into a final turn stall or they would have been more assertive making a go-around call. As to the first point, we all suffer from the “I can save this” philosophy because we have done just that so many times.  This new 605 pilot may not have understood that the Challenger series of aircraft do not react well to being loaded up in a turn and usually stall asymmetrically. (In this case, the low wing dropped abruptly past 140° just prior to ground impact.)  

Both pilots probably didn’t realize the aircraft’s weight and balance was out of date and 3,000 lbs. below actual weight, causing them to calculate their reference speed 6 knots too low. At some point the aircraft’s spoilers were deployed, reducing the stall angle of attack. Both pilots were either unaware of this effect or too task saturated to realize the boards were deployed.

Needless to say, both pilots made several errors on their way to crashing and I predict the NTSB will find both as causal. But a final note to contract pilots is in order. Being “guest help” on an aircraft requires tact and the ability to communicate in a way that gets your point across without jeopardizing future employment. But you must never allow the other pilot to exceed your limits.  

I was alarmed by the PM’s “let me have the airplane” request. My time as a contract pilot is limited, probably because of the one time I’ve been in a similar situation. “Let me have the airplane” is not in my lexicon.  My statement was not nearly so diplomatic: “Go around.” When the pilot didn’t respond I said, “Go around now or I’m taking the aircraft and we will go around.” He finally complied.