Ornis,

Perhaps you could direct your question to the manufacturer, who in turn could change the RFM to allow pilots to legally do as you suggest?

I'm a 135 driver of 12 yrs, with Police and 7 years Nvg experience on type. Maybe the guy ran down the supply tanks on purpose to check at what stage the low level lights would come on. Low level 1 was flashing and he waited for low level 2 to come on, before turning on what he thought were the transfer pumps. We may never know.

ofish, is it the sort of thing you like to try in flight then?

Please tell us you're a troll. You are, er, aren't you?

WTF? :ugh:

The pump was designed and certified for specific performance and the cumulative effects of running them dry (without lubrication and cooling) for longer durations than it would take to set them to the off position when convenient would shorten their lives considerably and create another problem.

SS & others - the message doesn't seem to be getting through that:
a) if a pilot operates the aircraft i.a.w. RFM, AND
b) if he understands the fuel system as he should, AND
c) if he pays attention to whichever CAD captions are showing, AND
d) (OPTIONAL - as I'm fully aware of both benefits & pitfalls of limited knowledge, but would rather they had some (which we encourage) than none) if TFOs have some understanding of the aircraft / captions / systems,

then it should not really matter whether there have been multiple sensor/CAD failures since . . .

1) if there's any doubt, there's no doubt - a safe landing at or before MLA or calculated (briefed) endurance should be the minimum expected, with any "embarrassment" being dealt with later, AND
2) you just don't turn both transfer pumps off, if there's any thought or suspicion that you might have fuel in the main tank.

Lots of "if"s above, but I'd argue that they're part of what's expected. Having flown the 135 for 10+ yrs, I just don't hold with the multiple failure theory, since there's certainly enough duplication in this aircraft, especially for those who know their systems, to have taken some mitigation action earlier.

Working close to limits serves to sharpen the mind, as previously mentioned.
efish :ugh: - I am as suspicious as wageslave :ok:, but if you were to try any game like that with our team, on a Police task; at night; at anywhere near that fuel state; whether CAD/captions were possibly working or not; you'd more than likely find yourself having a "robust debrief" with your TFOs which would probably bring all CRM skills to the fore!
In transit, by day, at a higher fuel state - maybe, but it's just not a viable theory in this discussion, IMHO.

No I'm not a troll. Silso knows who I am. I have over 30yrs military and police flying under my belt. And it's certainly not something I would ever consider doing. But I have to say its still a possibility, and I'm sure it will be one that the AAIB will look at. I'm as dumbfounded as most of my fellow aviators as to what could have caused this tragic accident. I'm not interested in blame, just plain facts.

I have nearly 3000hrs on 135. Many in police role. I was taught to manage the fuel and often flew to minimums. There is no flaw in this system, it just needs to be managed. Did you realise that 8 uk based aircraft have failed the fuel test in the last 6 weeks? Including Supply tanks showing permanent full and amber fuel caution not illuminating, first indication was reds.......
Info from latest CAA incident bulletin

Would that problem be very similar to having a Transfer Pump Switch turned OFF?

Yep, pump eventually fails, and how it fails is anyone's guess, it could be complete, intermittent, or not being able to deliver the required flow rate.

Would a permanent full indication be because the software logic in the display panel froze up or both supply tank sensors were giving a faulty reading?

DrinkGirls: the first useful and interesting though somewhat disconcerting transmission for ages. :uhoh:
This could be the crux of the whole disaster. This, OR pilot error.:\

Drinks, a link to the reports would be appreciated..
If 8 a/c have had serious problems with gauging errors then there does seem to be a flaw in the system....
Anybody have a link to a fuel system vent diagram...?
Anybody ever had blocked vents....which can lead to an over-reading contents?
Anybody know of a dual hydraulic failure in a 135...Is it flyable ..does it have accumulators in the system .?

Lets be totally frank and honest here. There will be very few people who haven't considered that pilot error is possible. Those of us who hope for something different will continue to question those who have made their minds up. This is why Sid gets his (totally undeserved) abuse on this thread. We know that the tanks and pipes to the engine were virtually dry, it ran out of fuel, the end. The red herring of spillover is VERY unlikely. However, the pilot MAY have been presented with confusing information. As SAS has stated, he should not have ignored the reds, but what if he really was confused by what he was presented with. What if his technical knowledge had not been reinforced and he chose to believe the gauges if they showed full supply tanks? What if, What if, What if?????
You see, no CVR means we DON'T KNOW what if!! This is where I struggle, because you cant convict someone on a best guess. Ignoring the reds is still pilot error.................. but did he??

If you say yes, please can you prove it??

No.

No.

Not enough to make any difference - i.e. used to dampen out pressure fluctuations but not to fly in the event of pump failure .

To clarify, I think 40odd made correct reference some while ago as to how the hydraulics pressure only drops off at the very last drop of Nr (if pumps are both working, of course), although it's obviously built with the redundancy of two systems.
I've not heard of a single HYD failure in a 135, let alone both. The forces on this fixed head system would require the strength of Samson (without haircut) to control without hydraulic assistance - doesn't bear thinking about.:eek:
Standard practice, in the event of a single HYD failure, is to land pronto anyway, lest the other one decides to throw in the towel, whereupon it would be uncontrollable. In addition, without any idea of system pressure (no gauges), you don't know what the second one's doing if the first one drops out.

I have not stated what has happened "IS" Pilot Error.

I have said the evidence so far has presented questions about what happened that Night that would support the notion the Pilot and/or Police Crew likely made some mistakes.

To attribute that to the simple notion and connotation of "Pilot Error" would be both unfair and premature until the AAIB Final Report is issued.

When we talk of what "We" would have done in that situation or such scenario's that have been presented....we have to remember "We" were not in the Aircraft that Night.

We do not know for sure what all the indications were....whether there were equipment or systems failures....or what actions were taken and why they were taken.....or not taken for that matter.

When I stated I would have carried out a Precautionary Landing if I was ever presented with two Red Fuel Low Warning Lights.....that is me speaking for myself.....and myself alone. Fortunately, I have never had that happen in an aircraft with the same Fuel System design as the 135.

When I say I would not.....and generally have not....turned off the Fuel Transfer Pumps.....that again is me speaking for myself....and not necessarily an approved or recommended procedure. That I very rarely had to run the Supply Tanks low Enough for the time a Transfer Pump would be "ON" and so devoid of fuel as to be a problem is due to my practice of landing before that became an issue.

I am not aware of ever having flown an aircraft that had a Transfer Pump fail or have to be changed due to a malfunction in a machine similar to the 135.

That I used a "Minimum Fuel" concept that forced me to land before both Red Fuel Low Lights illuminated also worked to prevent a dangerous fuel quantity situation from occurring.

Add to the Mix that I have absolutely no reservations about making Precautionary Landings and calling for a Fuel Bowser also ensured my not having experienced a desperate fuel situation in an aircraft with the same fuel system design as the 135.

Mind you....I have not ever had to make such a Precautionary Landing as I always found my way to fuel in a timely manner.

What happened to the Pilot and Crew of the Glasgow Aircraft will come out at some point I hope.....and even if there was an error or errors made by the Pilot and Crew....that we learn what the causes (Plural form used on purpose) and remedial actions be taken to prevent such another occurrence from happening again.

We owe it to those lost in this tragic mishap to ensure that is done.

If both transfer pumps have been switched off, and left off after one engine stopped, then the other, I don't think radio calls would be on my "to do" list. (Unless I was high and in sight of an aerodrome.)

Couple of things,

I don't know who efish is, clearly a comment to gain credibility on such a ridiculous post!
Zobra, why was that earlier post directed at me?

Lots to agree with in previous posts.

Except: DAPT, your suggestion is best described as DAFT! Mayday calls don't need to be mandatory. They are at the forefront of all pilots thoughts if ever immediate assistance is required. Until that moment in any cockpit process it is an unnecessary, even dangerous distraction!

And zorab, I genuinely don't want an argument however:
And
Do you see what difficulties you are creating here. Such CRM discussions should occur in the air, at the time, in order to potentially save life. Not in any "robust debrief"! But they can't precisely because there is only ONE aviation professional responsible for the driving! Some observers may have a little knowledge, some may not, but it's NOT a requirement nor a qualification. Otherwise you start to run into this problem:
Which is DEEPLY unfair to the relatives of the two police officers on board this aircraft, and the two officers themselves!

Really Sid, you must be getting forgetful in your old age! I put the scenario to you when talking on the phone the other week. I think your comment was a bit strong my old mate. I think I will leave this forum to the experts and wait for the AAIB report

You can't beat a good old steam gauge. When my fuel light is on, I can rock the airframe around and still "see" there is fuel in there slopping around. When the needle stops moving then I know I need to be on the ground.
KISS

TR,

I have flown both Police, EMS, and Nuclear Security tasks with Non-Pilot "Crew" Members in all three kinds of operations.

Despite the FAA seeing them as Passengers....we worked as a Crew.

They all were trained to monitor and assist the Pilot in various ways, were fully briefed upon normal and emergency procedures to the extent they had adequate knowledge to facilitate that assistance to the Pilot and to be able to monitor the flight parameters such as fuel endurance, routing, obstructions, terrain, weather, traffic avoidance, and other safety issues.

We also operated on the "One Dissenting Vote" Rule....for weather decisions and other safety related matters. Being the Pilot, in our system, we held the Veto Power......as our "No Vote" was final.

With that in mind, what I am suggesting is even though they were not Flight Crew per the official definition.....just as in our FAA view....the Police Crew have a role to play in the safe conduct of every flight just as did my Nurses, Paramedics, Deputy Sheriffs, and Special Response Team Members.

That Concept of Operation is my frame of reference when I said what I did about the Police Officers and the Pilot.
I mean no slight to the individuals but we do have to be honest in how we look at the situation......there were three "Crew Members" on the aircraft and they all had roles to play in seeing it being conducted safely.

If we take a Human Factors view of this accident, just as we should on each such tragedy, we cannot remove the Non-pilot Crew from the situation.