A Possible Advantage of Emergency declaration over a Pan

[pelmet]

This incident was well described by the TSB in their report. The bottom line was the aircraft which had declared a Pan Pan had to go around due to a previous landing on the runway. Not a particularly big deal in this case but it did create some inconveniences at a high elevation, mountainous airport at night. On the other hand, in a performance limited situation or some other difficult situations, the case may be that while there is not too much difficulty with an approach and landing, you would really rather not go-around. If that is the case, it my be advantageous to declare an emergency where hopefully, other aircraft are moved out of the way as compared to a Pan Pan. No guarantees but I believe it is more likely. One might want to even tell ATC that the approach should be kept well clear and departures stopped if the situation is critical.

"C-FHCJ, a B767-200 aircraft was being operated by Cargojet Airways Ltd., as flight CJT 951 from
Benito Juárez Intl - México Cit (MMMX) to Cincinnati/Northern Kentucky International Airport
(KCVG). While climbing out of MMMX, through FL290 the crew heard a thud noise coming from
the main cargo compartment. The crew also felt a pressure bump in their ears. Both crew
immediately looked to the pressure controller and noticed that the cabin rate of climb was well
exceeding 1000 feet per minute. Within seconds the cabin pressure altitude climbed in excess of
10000 feet, causing the Cabin Altitude light to illuminate and horn to sound. The captain, already in
the Pilot Flying Position, announced to the crew to don their oxygen masks and to establish
communications.

As the cabin was still climbing at a significant rate, the crew declared a PAN PAN with ATC and
requested an immediate descent. Initial descent clearance was given to FL200. An emergency
descent was initiated. The aircraft was flying over mountainous terrain at night, so considerations
were made for this. The captain requested the QRH for Cabin Altitude. The crew discussed options
and it was decided to return to MMMX. The captain utilized the PA to advise the ACMs to don their
oxygen masks and advised them of the problem. ATC cleared the crew to PAZ and then to ENAGA
for the ENAGA2B arrival for Runway 23L. This is the longest runway at MMMX.

Further descent was given when safe and in accordance with the arrival procedure. The crew
carried out the QRH procedures for Cabin Altitude and then Cabin Automatic Inoperative. These
checklists did not prove able to establish any control of the aircraft pressurization, although the first
officer was able to manually move the outflow valve but to no effect. Oxygen masks were removed
when cabin altitude was at a safe altitude. Arrival ATC cleared the aircraft for an approach and to
switch to tower. The first officer would advise each subsequent controller that they had declared a
PAN. The Tower controller advised the crew to maintain 160kias until MX402, the Final Approach
Fix.

They were number two to the runway for landing. Normal aircraft configuration was done and the
QRH Landing Checklist was completed. The tower advised to continue as the previous aircraft was
still on the runway. For some reason, the previous aircraft decided to clear at the end of a 13000
runway. When the crew reached decision altitude, no clearance had been given. The first officer
could not get a word in edgewise to obtain the clearance. The captain disconnected the autopilot
with the hopes of a late clearance but also ready for a go- around. At approximately 100 feet the
Captain initiated the missed approach procedure. Clearance to land was given while the aircraft
was well established in the initial go around procedure.

The crew carried out the published missed approach; ATC provided vectors for a subsequent
approach. The missed approach altitude was 12000 feet which triggered the Cabin Altitude
Warnings again. The crew donned their oxygen masks again until the aircraft descended as per the
approach to a safe cabin altitude. The aircraft approached and landed uneventfully on Runway
23L."

[Tbayer2021]

Thanks for posting this. Really goes to show how dynamic every situation is and the myriad of things we have to take into account, we have to stay vigilant and sharp. Every single broken wing scenario we practise in the sim at my company, allows flap extension to 20 degrees with the alternate system. First time we had a real life scenario, even the alternate system wouldn't extend them. So the crew had to land with the slats/flaps up.

[digits_]

Not sure how a mayday or emergency would have been different. It's not just Mexico either.

I witnessed an airplane with severe hydraulic issues (no flaps, manual gear, limited braking) declaring an emergency only to be told they were number 2 for landing behind a non-emergency aircraft. There was a lot of spacing, so no delays were anticipated, but if that plane would have been slow or stuck on the runway, the emergency aircraft would not have been able to land.

Makes you wonder how much 'what ifs' need to be covered in an emergency. Do you prohibit all landings when an emergency aircraft is 2 NM out? 10 NM? 100 NM?