Aviation Mythology and Misconceptions

[silverstrata]

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I thought I would start a thread on the erronious ideas that some professional pilots have. See how it runs, it might be interesting.

I will start it off with the argument from someone on this forum that you can do an ADF approach without an ADF. In short, he had misread the FCTM for the Boeing 737. But he may be a trainer - who knows. My answer was as follows:


Sorry, but you cannot do an ADF approach without an operating NDB and ADF - period !

If you do not have a ground station and the appropriate cockpit instrument, you are doing an RNAV FMC approach, not an ADF approach. And we have no RNAV approach plates in our Euro-Jepps, and so I'm presuming that RNAV (FMC/GPS) approaches are not yet certified to any of the airfields we visit in Europe.

Your reference in the 737 FCTM is referring to whether "raw data" or "map display" is selected - not whether the ADF is working or not. In other words, you can use map display mode, if you have overlaid VOR or ADF pointers for cross-checking (which many systems can do) or you flip between raw data and map display to check that the map is in the right position.

Note the note at the bottom of this section: - "Compare VOR and ADF systems to detect possible map shifts". You cannot do a map cross-check, if the VOR or ADF is u/s or not fitted !!


The 1996 Croatia USAF CT-43 crash is what happens, when people use a (map-shifted) RNAV FMC approach, instead of the raw NDB/ADF.


Ditto the B-Med Airbus going into Addis Abeba. The FMC plot and terrain display were off by some 3 miles, leading to a go-around just 60 ft over the high terrain. Now while the VOR would give occasional signals of its unreliability (the VOR was the primary fault), the FMC gave no indication that it had a map-shift. This was the biggest complaint in the report, that the FMC knew it was getting bum VOR information, and therefore may have a map-shift, but did not bother to tell the pilots. And the pilots could not check for a map-shift, because they were comparing bum data with bum data.


The map-plot indicated that the crew were highly influenced by the map and terrain display (rather than the VOR raw data), which showed them passing nicely through the valley. However, the terrain display was likewise mapshifted, and they were 3 miles north of the true inbound. If they had been following an erroneous and displaced VOR radial, it would have eventually taken them to the VOR, whereas this flight paralleled the VOR inbound, which is what would happen if you followed an erroneous FMC position on the map display. Which is why we do no do FMC approaches, especially when we do not have GPS input.

And I am not even sure that GPS-RNAV is entirely a solution at present (as was recommended in the B-Med report). It works well with high accuracy and reliability, but Europe is still concerned that the US may degrade GPS signals or switch the system off during periods of international tension. This is the primary reason for Europe developing and launching the Galileo GPS system. When that is up and running, and there is full confidence that erroneous signals can be detected and warnings given, then Europe may proceed to RNAV approaches.

[Clandestino]

Just a couple of myths I can recall in 15 secs:

Modern pax transport aeroplanes are capable of reaching coffin corner.

Mach stall exists.

FMS computed position obviates the need for brain computed one.

More experienced pilot is safer and v.v.

"Handling the Big jets" is obsolete.

FBW changes the aerodynamic behaviour of the aeroplane.

FBW is part of the autopilot.

You can not handfly an FBW Airbus in normal law.

With EFIS there won't be partial panel flying anymore.

EFIS display is basically digital.

Speed and altitude tapes are difficult to read.

With FMS taking VOR, DME, GPS, ADC and IRS inputs, there won't be map shifts anymore.

Turboprops are easier to handle and operate than jets.

Since, IAW our Mammonist doctrine, money spent equals dedication, sorting out merely hopeful from truly dedicated is best done by overpricing CPL training, making prospective pilot pay for type rating and topping it off by selling time in RH seat during normal pax ops.

What we read in "Fate is the hunter" is not applicable to modern airline ops.

---------------------------------------------------

As for Dubrovnik and Addis Abeba, what I recall is a slightly (an I really mean slightly) at odds with what you posted, I'll check my references and get back on it later.

[Wizofoz]

I was involved in a "Spirited' discussion here a few year ago with a Military pilot who fervently believed the "Killer Down-Wind Turn" myth!!

[old,not bold]

And then there's the myth that a B747-400 with one engine inoperative is precisely as safe as one with all 4 running properly.


Edit:

'Ere we go again. If the Mods want to kill it I won't be offended. Doesn't alter the fact that it's a myth, though.

[Shiny side down]

A number of odd ones encountered in very recent years

Myths-
Reduced thrust takeoff is for fuel savings

Temperature of fuel has no effect on volume uploaded

VS is safer than VNAV. (statement: VNAV is dangerous. Do not use it, use VS instead)

QFE Meters is the same as QNH feet

A professional pilot is one who safely busts MDA and finds the airfield in fog

[AtoBsafely]

Silver,

"Sorry, but you cannot do an ADF approach without an operating NDB and ADF - period ! "

There are jurisdictions where the overlay approach IS automatically authorized with an approved GPS-FMS navigation system.

Not an absolute rule.

[Clandestino]

I meant to post "Pilots don't understand difference between RNAV overlay and underlaying approach" but I'm having second thoughts. I'm not sure it's a myth anymore.

Originally Posted by old,not bold

And then there's the myth that a B747-400 with one engine inoperative is precisely as safe as one with all 4 running properly.

Never heard of this one. Methinks original myth was "It is under no circumstances safe to cross the pond on three out of four engines"

[misd-agin]

737NG approach speed has been increased due to fuselage length(-800 models).

Turning into the 'dead' engine is dangerous.


Forgot about the previously mentioned 'dangerous downwind turn'.

[OutsideCAS]

"Wow, your a pilot - you must earn loads of cash"

Biggest non-pilot mis-conception ever there.

[barit1]

An old, old myth

Passengers will never choose to fly transoceanic on less than four engines!

[rudderrudderrat]

Turning into the 'dead' engine is dangerous.

It was on 707s!

The published VMCA figures increased by 20kts with wings level and we only had one hydraulic system running the Rudder boost. If you lost that - the VMCA increased by about 60 kts.
(See accident report for B707 base training accident Prestwick Airport in 1977)

Edit should be "VMCA figures increases by about 40 kts wings level"

[Clandestino]

The published VMCA figures increased by 20kts with wings level

I can't wait to see this one explained.

[rudderrudderrat]

Hi Clandestino,

Then wait no more. See Page 20 para 2.4

http://www.aaib.gov.uk/cms_resources...8%20G-APFK.pdf

[con-pilot]

All pilots are treated with a great deal of respect.

There is one for you, as someone else already posted the one about being paid a great deal of money.

Then there are the old jokes.

"I wish had as many affairs on the road as my wife thinks I do."

"I wish I made as much money as my wife spends."

"I wish I had as much time off as my neighbor thinks I do."

Feel free to add more.

[Clandestino]

Thanks Rudderrudderrat! It makes perfect sense

So turning into dead engine actually is dangerous on the highly-swept-winged aeroplanes with indifferent rudder and 5° bank into live was not just drag reducing measure as I was taught but necessity to get a certain aeroplane certified with low enough Vmca.

EDIT: That would be another myth busted:

Creatively interpreting the certification criteria to effectively bypass them is Toulouse specialty.

[Sir George Cayley]

You can only land on grooved runways in the wet.

SGC

[Old Smokey]

#1 Jet aircraft do not exceed Mcrit in normal operations.

#2 Long Range Cruise speed is the speed for minimum fuel burn.

#3 Best Rate of Climb speed provides the best sector fuel burn.

Regards,

Old Smokey

[frontlefthamster]

I'm astonished we've got this far down this thread without the biggest myth of all...

Safety is our first priority

(by the way, you don't need swept wings to make turns towards the inoperative engine hazardous, though I've only found it a significant problem on pretty ancient aircraft)

[fireflybob]

How about airline pilots are millionaires and all they do is sit there and push buttons all day because flying now is "automatic"?

[wilyflier]

Wizofoz and downwind turn

Just you try the difference between a downwind turn and an into wind turn when you are near enough to the ground to detect it, i.e. on a hang glider.
Its no myth. Its all about energy states between aircraft and ground.