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What goes through your mind as you approach minimum on an IFR approach?

As a VFR pilot, I’ve never flown an approach to an airport to minimums. But this thread got me wondering.

What goes through an IFR pilots mind as they approach minimum and still can’t see anything outside?

Are they thinking:

“Crap! I’m approaching 200ft above the ground and I still can’t see anything. I’m so close to stuff that could kill me but can’t see it! This is getting scary and I want to get out of here…don’t want to go all the way to minimum!”

or are they thinking

“This cloudbase can’t go all the way to the ground. Just a few feet beyond minimum can’t hurt! There’s still 200ft between me and the ground…..I’m sure everything work out fine if I go down just another 50ft”.

I appreciate that that training is to go around at minimum, and I’m not asking if people bust the minimum on purpose. Rather I’m wondering about the Psychology of it. What is the thought process and the pressure that a pilot fees as they approach minimum on an IFR approach and can’t see outside.

Does that answer to that question change with experience and/or currency?

EIWT Weston, Ireland

dublinpilot wrote:

Does that answer to that question change with experience and/or currency?

Not in my personal experience. Or rather on the contrary: In my early years of IFR flying, I sometimes felt tempted (*) to think: " going down another 50ft can’t certainly harm ". With the years it rather turned into “minimum … no contact … go around!”. Doing it that way there is no scare involved at all ( like your " don’t want to go all the way to minimum! ") because at the minimum you are guaranteed to be free of obstacles. No need to worry. But lots to worry when you are at minimum minus 50 or minimum minus one hundred. Believe me.

But I have flown as co-pilot with some old and very experienced pilots (all examiners and senior examiners on transport category aircraft) who, on a bad weather day, would ask " what’s your minimum? " before turning on the battery, so that the answer will not be recorded on the voice recorder. Just to make sure that no discussion would come up when approaching the minimum later on. The “minimum!” call would then only be given at the agreed value… Never asked one of my co-pilots that question. Minimum is what’s on the chart, even if I am a living proof of the contrary.

( * ) I will not publicly disclose whether or not I ever succumbed to that temptation

Last Edited by what_next at 24 Jan 15:51
EDDS - Stuttgart

…on centreline…on glideslope…300…on centreline…on glideslope…250… looking up…crap…still crap…minimum – going around. [shrug shoulders, divert]

Or:

…on centreline…on glideslope…400…slightly left, correcting … 350 .. bollocks, needle still moving left, – going around. [be annoyed, try again or divert]

Mind you – this is reasonably rare; personally I have had a ONE flight where visibility was marginal (1000m or less), a few times where cloudbase was 200-300ft, and one diversion; at around 250 hours IFR and 100 hours “sole reference” I don’t have that much experience.

But in the same way that most newly minted pilots are reasonably confident that they can get an aircraft to the ground safely or can go around for another attempt, I was confident that I can fly an approach or, if I get it wrong, go around.

Biggin Hill

The answer is only black and white in the same way that cloudbases are exactly flat.

The difficulty is neither when you can clearly see the lights, nor when all you can see is grey. In those two circumstances the answer is too obvious to write.

But it’s when you look up and you can see the surface murkily, and street lights and car headlights, and you have to adjust, not so much your eyes as your pattern recognition, to be sure that the lights coming through the gloom are the lights you want.

Obviously, the better the lights, the easier that is, and in many large airports there are huge stroboscopic lead in lights, starting hundreds of metres back, which makes the task very easy. But if you are going into a little GA place with a tiny christmas tree, it can take several seconds.

And so the difficulty is knowing, and then being disciplined enough to act on, the number of seconds you are willing to keep peering and orientating yourself, while you continue to descend.

It is also important and difficult to discipline yourself to stay on the slope as you do that. It is very tempting to drop a tiny bit beneath the slope (ie point at the ground) and that is a real killer.

A fully coupled autopilot is a godsend in these circumstances, as you can be confident to look out for a few seconds without having to keep looking back in at VSI and glideslope. Which is why single pilot minima are 800m without an autopilot and system minima (usually 550m) with.

It is worth doing a calculation.

Cat 1 ILS is typically 3°, 200’, 550m. On a 3° slope, you are at 200’ ⅔nm from the touchdown point. ⅔nm is 1235m. 1235m is 2¼ times 550m.

That means that at minima on a Cat 1 ILS, you can never see the touchdown point from Decision Altitude. You can’t even see half way to the touchdown point. So you will never see the PAPIs. All you will see is the beginning of the approach lights.

Thus, if you really are at Cat 1 minima, the decision is taken at DA (based on the approach lights), but you cannot fly visually based on the little bit of approach lights you see, so, having decided to land, you then have to stick your head back inside for another 100’ (ie 10-20 seconds) then look up, at which point you see the PAPIs and piano keys.

Is it scary? No, not once you are used to it. But it does require accuracy and discipline.

Last Edited by Timothy at 24 Jan 16:18
EGKB Biggin Hill

Timothy wrote:

And so the difficulty is knowing, and then being disciplined enough to act on, the number of seconds you are willing to keep peering and orientating yourself, while you continue to descend.

and

Thus, if you really are at Cat 1 minima, the decision is taken at DA (based on the approach lights), but you cannot fly visually based on the little bit of approach lights you see, so, having decided to land, you then have to stick your head back inside for another 100’ (ie 10-20 seconds) then look up, at which point you see the PAPIs and piano keys.

I had wrote a long response but then deleted it. Suffice to say, I completely disagree with that philosophy.

Fly safely
Various UK. Operate throughout Europe and Middle East, United Kingdom

Dave_Phillips wrote:

I had wrote a long response but then deleted it.

Interesting. I had written a medium long response in favor of that philosophy and then deleted it, because I thought it didn’t contain sufficiently new ideas…

My main point was: Arriving at CAT I minima in CAT I conditions you really only see a few approach lights. Often not even aligned with your aircraft as autopilots/flight directors tend to crab the aircraft into wind. There are exactly zero visual cues from which you can derive your attitude, sink rate and speed. I have had students (and co-pilots) almost killing me by not looking back inside at their instruments but trying to line-up the aircraft with the runway based on those four dimly visible approach lights. We ended up over the threshold banked 30 degrees and pitching down 10 degrees… You can recover that in a Pa28 but in anything over 5 tons it is scary.

EDDS - Stuttgart

In my 15 years of IFR flying I haven’t had many instancies where I had to fly to minimums. My flying skills were best just after I got the license. I always handfly approaches even in VMC with my head down on the instruments but that is not the same. your stress levels are nit nearly the same. I didn’t feel comfortable yesterday as the info I had was not matching reality and with the info I had I was expecting to land.
The game that plays to psychology is very subtle and we are just hobby pilots no cool well trained prof dude.

I didn’t feel comfortable and in my case the uncomfortable feeling increased the moment I discerned a bit of ground looking down at the minimums. This did not boost confidence to proceed a bit further.

I appreciate that others have different ways to react.

LSZH

I take the question to be linked to ILS CAT 1. The Approach Lighting System (ALS) for an ILS is designed to help transition to visual at DA, in effect creating a horizon helping orientate towards the touchdown zone and Runway End Identifier Lights. The so called ‘rabbit’ described by Timothy is used in the USA, but not that common in Europe. The whole ALS system is designed to penetrate the gloom of low IFR, hence you have RVR conversion factors linked to the availability of ALS.

What this means is that you need to see the ALS at DA, including the REIL, not just some approach lights which you can probably see looking straight down.

It takes around 12 seconds to adjust trajectory and only around 20 seconds from DA to touchdown, hence the need to be on slope and localiser, and stabilised at DA. Dipping down to say CAT II without the necessary training and equipment, means you have no time to adjust trajectory and remain in the protected zone, hence many, many accident reports of aircraft crashing on approach in low IFR.

What does this look like at DA, like a Christmas tree where the top of the tree is visible, even though there still may be low level cloud given the geometry described by Timothy.

In short if the ALS is not visible reasonably comprehensively at DA GO AROUND – your approach brief should cover the ALS you are expecting to see at DA.

The FAA Handbook, which merits close reading, has quite a good description of this at Section 9 -38.

Oxford (EGTK), United Kingdom
Approach Lighting System (ALS)

sincere thanks, @Robert!

EBZH Kiewit, Belgium

RobertL18C wrote:

What this means is that you need to see the ALS at DA, including the REIL, …

At CAT I minima of 550m / 200ft there is no way you see the REIL at decision altitude. At 200ft DA on a 3 degree glideslope you will be 2/3 of a nautical mile away from your touchdown point. That is 1230m. The touchdown zone is 300m behind the threshold, so you will have to run 930m to the runway edge. Almost twice your 550m visual range or plenty of seconds to fly until you actually see the runway.

EDDS - Stuttgart
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