No TCAS, no flight
 

Horizon in the US unable to use exemption common to other airlines.

https://www.seattletimes.com/busines...lision-system/

"FAA policy has long allowed airlines up to three days’ leeway during which they can continue to fly a plane with an inoperative system.

But Clint Laurie, the FAA’s principal operations inspector at Horizon, supported by his team that oversees the airline, is enforcing a strict interpretation of the TCAS regulation."

Is Laurie an FAA employee or is he a Horizon employee designated by the FAA as an inspector? If the former, that would seem to be a problem; i.e., he’s implementing an operational restriction that’s inconsistent with the policy of his employer. If the latter (more likely), he’s simply implementing an operational constraint that’s more restrictive than existing FAA regs/policy, but is doing so under the authority of Horizon.

Cynical half-measure?
 

This also from the Seattle Times article:
SLF here. I'd appreciate that as a prospective Horizon customer. It begs the question: what about the safety of other operators' passengers? Or flight crews, including those at Horizon?

By title, I'm going to assume FAA employee.
The FAA Master MEL, depending on installed avionics equipment, states 2 flight days (Cat A) or 3 days (Cat B), Note, the Horizon MEL may be more restrictive.
14 CFR 121.356 says you have to have one. I wonder if the "exemption common to other airlines" are to the Rule, and Horizon just does not have that, hence the issue.

That's ridiculous. How can a lone FAA inspector unilaterally apply, to only one airline, a rule that overrides the legal document that we all operate to, the MEL?

By all means change it but any change must apply to all operators.

Perhaps you shouldn't go flying, John. And remember that the other aircraft will have a serviceable TCAS which will issue a avoidance manoeuvre to the other crew if needed (unless of course it too is operating under the MEL with a U/S TCAS; highly unlikely). TCAS is not required in both aircraft.

Considering how crowded our skies are today, I've always felt strongly that systems like TCAS (and preferably also GPWS/EGPWS) must always be operative.

Is there any chance Horizon have, perhaps, been loosely interpreting some rules, and are now being hit with a crackdown to make them toe the line? Just wondering.

Really? So if your magic computer breaks at some remote location miles from nowhere what do you do to get someplace to get it fixed?

What I implied was, that TCAS INOP should be a non-dispatchable condition... of course, a ferry flight would be permitted... but really though, considering how 'see and avoid' is clearly deficient at modern airliner speeds, and under high workloads, is it really safe to dispatch a flight without a working EGPWS/TCAS ?

Aviation has reached such heightened levels of safety, owing a lot to the automation and safety systems, which serve to significantly enhance Sit. Awareness... and permitting revenue flights without them, IMO, is a mistake.

Moreover, the Earth is littered with ground surfaces these days.

I wholeheartedly agree - it is blatantly unfair to hold one operator to a higher standard than everyone else.
So, if you're going to allow a ferry flight - if that results in a mid-air due to the inop TCAS, the other aircraft - presumably a revenue flight with a full load of passengers - is also going to crash. How are you going to prevent that if it's so unsafe to have a flight without a working TCAS?

It is not unsafe to fly without TCAS. For there to be an issue, the other aircraft would have to not have TCAS as well, like the piper cub on floats crossing the LLZ outside of the veil in PANC... who doesn't need an electrical system. I own a jet that was used for TCAS testing, and the failure rate of TCAS is enough to strand pax in various parts of the world, by the number of times the system was swapped out for repair.

Is there a particular accident you are referring to, where a TCAS or TAWS system was MEL'd and the crew had a bad day? The primary means of traffic and terrain separation (well, departure can be slightly different) is ATC, then alerting, then a pilot that is competent and awake.

If I was getting TCAS RAs everyday I might agree with you, but the only RAs I’ve ever had were “nuisance” alerts where one aircraft was levelling off 1000’ above or below another. There’s also the point that, unlike doing the Tango, it only takes one to TCAS RA, so provided the MEL alleviation is short enough that the chances of coming across another aircraft operating under the same MEL are low enough, I’m comfortable with it as it is.

Which equipment is used in this aircraft ?

A stand alone ACAS / TCAS; or a combined system, T2CAS which has both ACAS and TAWS functions in one 'box'.
Which ever, how does the MEL provide alleviation for the different systems ?
Does the MEL differentiate between hardware (box) and the function; e.g. power supply or sensor input.

Anyone recall the saying "Two TCAS North of Darwin".
Reflecting a safety culture (and perceived hazard) as much as the system availability.

The tragic mid air between that Embraer and the 738 is an example, not to mention the dozen or so near misses that TCAS has prevented.

I do agree, yes, Aviation wouldn't be unmeasurably unsafe if it weren't for TCAS. I'm just saying... aviation is all about reducing risk, and allowing a flight sans TCAS/GPWS IMO isn't a great idea.

PS. I totally forgot to mention, sorry, that IIRC, the Transponder went INOP mid flight

Zar, I don't think you really understand the purpose of the MEL. In a perfect world, every aircraft would takeoff with every system working perfectly, pilots would always be well rested and alert, and ATC would never make a mistake.
The world's not perfect. Things break, pilots fly fatigued, human pilots and ATC make mistakes. S*** Happens. IF we required every commercial aircraft to have every system fully functional in order to carry passengers, the whole aviation industry would grind to a halt - Delays and Cancellations would skyrocket, people would be completely unable to count on it. Commerical aircraft - heck the entire aviation industry - is designed with high levels of redundancy. That's the major reason why aviation is so safe. Sometimes some piece of that redundancy fails - a component fails, a human makes a mistake - but the redundancy takes over and keeps things safe.
Considerable effort goes into development of the Master Minimum Equipment List - MMEL. Almost without exception, items on the MMEL allow for a failure that results in a loss of redundancy. That loss of redundancy is evaluated - how serious is that redundancy loss, what's the consequence of the next failure, what's the likelihood of the next failure. Then the airframer and the regulators get together and determine what is acceptable without a measurable impact on safety - and for how long. It's accepted that there will be a tiny reduction in the margin of safety, but the effect on the overall safety is negligible. It allows aircraft to keep flying, to get back to a maintenance base where it can be fixed properly. And remember, the pilots get the final say - if they decide it's not safe to dispatch with a particular system (or systems) deactivated via the MEL, they can say NO (not saying there won't be pressure to go, but remember the pilots are usually the first ones at the scene of a crash so they have a vested interest to refuse something unsafe).
Dispatching an aircraft with an INOP TCAS reduces the redundancy of the system, but you still have two more levels - ATC and TCAS on the other aircraft - before it becomes unsafe. It's been judged acceptable to do that for three days.

Oh, BTW, Überlingen was one of the worst midairs in history. Both aircraft had fully functional TCAS systems at the time of the crash. As I said, somethings :mad: happens.

Well said tdracer.
To add a bit of first hand ATC knowledge, actually when we study Mode S downlinks , we find that over half of the RAs generated by TCAS are not followed correctly, some of them not at all, and even sometimes flown in the opposite direction ( which was the case in Ueberlingen mentioned by tdracer. )
And then there are the TA-only pilots , for some obscure reasons there are still pilots that fly in TA mode only , which means they are not protected . In Europe ( and suspect similar figures in the US) we find aircraft involved in incidents ( airproxes) with one aircraft being on TA mode
And I am not talking about close parallel approaches where you may switch to TA only.
From a reecent Eurocontrol safety bulletin :
Then ,taking all this into account, adding your 2 or 3 aircraft flying with an INOP TCAS for max 3 days is not treally that releveant.
Relying solely on TCAS to keep you safe is not a guarantee you will never meet someone one day .

Yes, sorry, I totally forgot that an INOP TCAS wouldn't lead to a total loss of traffic awareness (we do have the ATC and TCAS on the other ac).

All,
MMEL's are written as far as I know against the aircraft certification rules, in this case 14 CFR 25, or the EASA equal. The FAA team that writes the MMEL does not know if you are going to operate the aircraft Part 91, Part 121, Part 135 etc. Each operator has to then take the MMEL, and update it for their operation, and submit it to the FAA for approval.

That is an operational rule and without the exemption (if that is the case) Horizon cannot fly and the inspector is correct. Each airline has to apply for the exemption as far as I know.