Minimum Safety Altitude
I was checking a sudents plog today and noticed he had put an Minimum Safe Altitude of 2200 ft , and a planned altitude of 2000ft, i asked how he came to this figure, its MEF plus 1000 ft came the reply, seems he was told this by another instructor, not wishing to rock the boat at this point i let him go on his x/country, BUT , surely the Minimum Safe Altitude should be an altitude you come down to if forced by bad weather, so should be based on things like 500ft above the tallest mast on route, 500 + 300 on top of highest ground or 1000 ft above built up area etc. etc. not some random 1000ft above an MEA on some large box on the map, :ugh: how do you calculate the Minimum Safe Altitude on a students plog?
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Firstly, what do all the TLAs mean?
The Minimum Sector Altitude (MSA) is the lowest altitude which may be used which will provide a minimum clearance of 300 m (1 000 ft) above all objects located in the area contained within a sector of a circle of 46 km (25 NM) radius centred on a radio aid to navigation. These are the segmented circles on the top of Jeppesen plates (an others). The minimum en-route altitude (MEA) is the altitude for an en-route segment that provides adequate reception of relevant navigation facilities and ATS communications, complies with the airspace structure and provides the required obstacle clearance. I'm guessing that doesn't apply to our PPL student. The Maximum Elevation Figure, and the Minimum Off-Route Altitude (which is what I think you've got MEA confused with), are the figures in the 1/2degree boxes on the charts. On the CAA VFR charts, they are the MEFs, which are the figures for the highest known object or highest terrain plus 300' in that box. On the Jeppesen IFR charts, they are MORAs, which *include* the safety factor of 1000' for terrain up to 5000', and 2000' for terrain over 5000' (or higher if national regulations require). In the UK, Minimum Safe Altitude is a hang-over from days of old. Frustratingly, not defined legally anywhere! We all know what we think it ought to mean, right? In EASAland, we have minimum flight altitudes. The 'operator' should define what these are, and how they shall be calculated. You may have one minima for VFR and another for IFR. In other words, what does it say in *your* school's NCO Ops Manual / training manual / flying order book? Traditionally, "MSA" is the f**itimscared bolt-hole altitude that one should climb to if VMC is lost. It is NOT the minimum altitude that you can fly at VFR. To be IFR (and in IMC below 3000'), one must be 1000' above the highest obstacle within 5nm at all times. So, during planning, an additional lateral margin is applied so that if you are reasonably off track, your bolt-hole altitude will still be IFR legal. Most schools/operators will define this margin as 10nm either side of track (and around the turning points). If your navigation aids are limited and position cannot be accurately known, then wider margins may be required - ie, a long leg between any viable fixes may see you drift significantly further than just 5nm off track, in which case you might use a cone of ever widening safety! Usually, we get Plt Off Prune to scour his chart with a thumb either side of his track (10nm), picking out the tallest objects and highest ground en route. We then add 1300' to all the terrain and 1000' to any obstacles, and the highest figure will be the "Safety Altitude" (or whatever you want to call it). In the case of your student adding 1000' to the VFR chart MEF, they're not too wrong... It's not a good idea at a planning stage though, as you could be a) pushing yourself in to cloud at one end of the box for a tall mast 30+nm away, and b) ignoring an obstacle 1nm away in the next box along! The MEF/MORA are better applied when thrown off course and a quick and dirty assessment is required. |
Surely MSA is only an IFR concept - remaining at least 1000ft above anything within 5nm at all times. It has no relevance VFR.
Of course the concept of a minimum safe altitude (note non-use of capital letters) is relevant in VFR ops, but beyond being legal, it should be about a rational judgement about always being able to handle an engine failure, not bump into anything, and being unlikely to inadvertently enter controlled airspace. What is sensible will depend upon multiple factors, of which the numbers marked on a chart for IFR flight planning, and not one of those factors. The use of simple factors and numbers, getting pilots - including student pilots - off the hook of looking hard at the chart and forming a useful judgment, does not seem to me wise. G |
Minimum Height Rule was Rule 33 of the UK Rules of the Air and was one of the Instrument Flight Rules however; that disappeared on the introduction of SERA where the Minimum Height rules for VFR operation can be found in SERA.5005(f)
(f) Except when necessary for take-off or landing, or except by permission from the competent authority, a VFR flight shall not be flown: (1) over the congested areas of cities, towns or settlements or over an open-air assembly of persons at a height less than 300 m (1 000 ft) above the highest obstacle within a radius of 600 m from the aircraft; (2) elsewhere than as specified in (1), at a height less than 150 m (500 ft) above the ground or water, or 150 m (500 ft) above the highest obstacle within a radius of 150 m (500 ft) from the aircraft. surely the MSA should be an altitude you come down to if forced by bad weather, For IFR Operation under SERA replacing Rule 33: SERA.5015 Instrument flight rules (IFR) — Rules applicable to all IFR flights (b) Minimum levels Except when necessary for take-off or landing, or except when specifically authorised by the competent authority, an IFR flight shall be flown at a level which is not below the minimum flight altitude established by the State whose territory is overflown, or, where no such minimum flight altitude has been established: (1) over high terrain or in mountainous areas, at a level which is at least 600 m (2 000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft; (2) elsewhere than as specified in (1), at a level which is at least 300 m (1 000 ft) above the highest obstacle located within 8 km of the estimated position of the aircraft. |
Which is why the UK's "MSA" is a term that needs to be scrapped. (Along with QFE! :) )
I was taught it as an emergency minimum, RAF style... something to climb to if you loose references/get lost etc. Others use it as a minimum en-route altitude for all parts of VFR flights. Minimum Safe(ty) Altitude is NOT defined anywhere, and so it means different things to different people. That's just dangerous. Safety Sense leaflet 5e talks about "minimum altitude" during planning (4d), "Safety Altitude" when lost (7d), and finally "minimum safe VFR altitudes" in the conclusion (11). If the CAA can't decide... This is why I promote the more EASA like terms: Minimum flight altitude for route segments (may be different for VFR and IFR plans, as defined by your ops manual, which would suit the descending against worsening weather), and a Safety Altitude to shoot to if it all goes white. |
I was taught it as an emergency minimum, RAF style... something to climb to if you loose references/get lost etc. |
Great information guys, although i'm just talking about a 20 hour VFR student, i dont want him to climb to 2200 feet if he gets into cloud, before he gets into cloud,i want him to be aware of his worst case 500/1000 ft rule altitude, probably also setting the regional QNH,then if he cant continue, turn round and go back to his point of departure.
I shall revisit SERA and the safety sense leaflets. |
I remember the days when you had to scour a map looking for the highest elevations and then perhaps missing one. There was also the posibility of uncharted masts, so the introduction of MEF figures for each map square really took away all the hard work.
For VFR you only need to look out of the window and have an idea where the high ground or masts are. MEF + 1000 feet provides a practical safety margin however; so long as you don't infringe the minimum height rule you can fly at whatever altitude you like. If the weather becomes an issue, current teaching is to do a 180 degree turn and go back to where you know its better. This is a skill test item. |
I agree that the 180 degree term is a skill test item. but the CAA approch was a bit simplistic. As I saw it opon enter bad weather, the student should make a 180 degree descent down to MSA, if above MSA, consider which direction the bad weather is coming from based on form 215, consider the option for diversion, and request QDM's or radar.
The AAIB report on G-BIIJ, says it all. I would add that on a cross country it is sensible to apply MSA for students or inexperienced PPLs. even in VFR. It also means you are less likely to be in conflict with miltary and rotary wing aircraft. |
I would add that on a cross country it is sensible to apply MSA for students or inexperienced PPLs. |
I make a point of asking the candidate on every test to explain what they understand by MSA, since they have written it down on their plog.
None of the candidates except one has been able to explain any of the figures. I keep feeding this back to the instructors, but they don’t understand it either! |
Originally Posted by Broadlands
(Post 9983974)
I make a point of asking the candidate on every test to explain what they understand by MSA, since they have written it down on their plog.
None of the candidates except one has been able to explain any of the figures. I keep feeding this back to the instructors, but they don’t understand it either! |
Exactly the point I make. The misunderstanding originates in training by instructors who quote MSA but don’t actually understand minimum altitudes etc etc, thus a candidate quotes a figure but can’t explain properly where it came from or how to use it.
It’s always a good debrief item, one which hopefully leads to good decisions being made in their future flying. |
Originally Posted by Genghis the Engineer
(Post 9980092)
Surely MSA is only an IFR concept - remaining at least 1000ft above anything within 5nm at all times. It has no relevance VFR.
Of course the concept of a minimum safe altitude (note non-use of capital letters) is relevant in VFR ops, but beyond being legal, it should be about a rational judgement about always being able to handle an engine failure, not bump into anything, and being unlikely to inadvertently enter controlled airspace. What is sensible will depend upon multiple factors, of which the numbers marked on a chart for IFR flight planning, and not one of those factors. The use of simple factors and numbers, getting pilots - including student pilots - off the hook of looking hard at the chart and forming a useful judgment, does not seem to me wise. G |
Student (and instructor?) needs to revise VFR regulations. its MEA plus 1000 ft came the reply, seems he was told this by another instructor, |
What is wrong with briefing an MSA for a VFR sortie? In the case of IIMC, that is what you want to climb to.
Yes, in an ideal world, the student will turn round/descend/divert before the IIMC scenario but we all know things often don't go as planned. If he/she has a number on their map that they have thought about/briefed that will keep them away from obstacles/the ground if it all goes Pete Tong then who cares if they confuse Min Sector Alt with Min Safety Alt? You can argue that MSA isn't relevant to a PPL VFR student but it will be in their future careers so why not teach it and include it from a early stage? Reversion to IFR (planned or unplanned) is always a consideration in operational flying so get the concept and the terminology started from grass roots. |
What is wrong with briefing an MSA for a VFR sortie? In the case of IIMC, that is what you want to climb to. Obviously, it needs to planned in advance and kept under review in flight, leg by leg (especially if flying near/under controlled airspace). |
You can argue that MSA isn't relevant to a PPL VFR student but it will be in their future careers so why not teach it and include it from a early stage? We went through a phase with a UK PPL where 4 hours instrument training was mandatory however; in some cases that encouraged pilots to fly on instruments with a bare minimum of training. The European licence removed that 4 hours and teaches only enough instrument flying to do a 180 degree level turn untill you become visual again. The LAPL doesn't even include that training. Teaching a VFR pilot to climb to a Safety Altitude for instrument flight is of no use if they can't get back down again. |
Bit of a broad assumption. The average PPL never goes beyond being a PPL and never gains an instrument qualification. They might get VMC on top or find a big gap to let down through - a whole lot better option than grovelling around too low in poor weather. The European licence removed that 4 hours and teaches only enough instrument flying to do a 180 degree level turn untill you become visual again When we tracked their 121.5 beacon and broke cloud at the very top of the hill, we saw them waving from the corner of the wood and took them (uninjured) home. You can't ignore the need for some basic IF skills with UK weather unless you never go flying - if a few use those skills unwisely then that is their lookout. |
Absolutely so whoppity, i cant believe anybody would advocate a student climbing into further IMC, just madness, without knowing where the tops were or knowing how to get back down again, where the 0 degree isotherm is, i would never advocate going IMC without positive radar identification beforehand, students, stay VFR!
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So, if they are IIMC with high ground around, what would you suggest they do?
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Follow the teaching, turn 180 degress level and hopefully you will fly out of it. At least you should have an idea of the terrain you have just flown over rather than pressing on into the unknow. The main emphasis is to stay VFR and act early. There is no majic solution for those who plough into IMC and have no knowledge or training on how to get out of it.
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turn 180 degress level and hopefully you will fly out of it. If you are carrying out a rate one turn IIMC you have no idea what you are turning into since you can't see it - exactly as I indicated in my dit about Swansea to Shobdon. They followed the training and would have all died if they had better IF skills. Turn before you get to the crap weather by all means but once in it you are flying IMC below MSA - tell me how that is a good idea? |
Some years ago I had a student who had completed the 4 hours IF. Once he had his licence he flew off to France where he inadvertantly got into IMC. He climbed to the safety altitude and was now in solid IMC. Nobody to talk to and no real idea of where he was. Eventually, he found a hole and descended. Afterwards we discussed it and he agreed that if he had not found the hole the probable outcome was not good. Had he simply turned around, there is a higher probability that he would have regained his visual references earlier and without the anxiety he caused himself and his passengers by climbing into the unknown.
The emphasis for the VFR pilot must always be to stay visual and when in areas of high ground be aware of the location of it and the possible oragraphic effects. The 180 degree turn is based upon the assumption that you have only lost your visual references for a few seconds. Climbing to Safety Altitude presumes you are competent at instrument flying and have a means of recovery. |
Problem comes when the 180 degree turn is completed but the pilot still finds himself in IMC. Easily done if there was any delay in beginning the turn.
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Hang on in there, it seems to take seconds to be IIMC, but ages to come out of it.
The students adrenalin starts pumping, the stress level increases, just do the 180 turn, get back to VMC. |
I am constantly amazed by my students' apparent inability to detect approaching cloud (either whilst in the cruise or when climbing), their willingness to continue flight in to it as visual references rapidly degrade and their reluctance to take prompt action to avoid it.
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The 180 turn is great when you have lost forward references but still have contact with the ground - you can turn with a slight descent which may well pop you out of cloud with just an elevated heartrate to contend with.
Trying clever manoeuvres solid IMC - because you have waited too long - is a recipe for disaster; disorentation in a turn and probable loss of control or CFIT. At least wings level in a climb away from the ground, you have a chance of sorting yourself out - even if it is just crying for help on the radio and being guided by a friendly air trafficker to a safe let down area (it has happened countless times). |
crab
With all due respect to your opinion what we must remember is this: The student is only required to learn straight and level and a 180 rate one turn. This is generally accepted to be a one hour flight and the majority of them manage to get to an acceptable standard in that one flight. There is no requirement to teach any IF climbing or descending or turns whilst doing so. Since all their flying training should be conducted using the natural horizon they will not know how to climb or descend on instruments safely. My initial four hours during basic training saved my life , but only because I didn't try to climb. |
(all except the one hour)
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Right with you on the VFR minimum alt TA, I meant to say exactly the same.
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There is no requirement to teach any IF climbing or descending or turns whilst doing so. Exercise 19: Basic instrument flight: (A) physiological sensations; (B) instrument appreciation; attitude instrument flight; (C) instrument limitations; (D) basic manoeuvres: (a) straight and level at various air speeds and configurations; (b) climbing and descending; (c) standard rate turns, climbing and descending, onto selected headings; (d) recoveries from climbing and descending turns. The LAPL does not include Ex 19 at all. |
Thanks Whopity.
I've always managed to convince students to learn b, c and d but didn't realise it was mandatory. That just makes it easier to achieve in the future. Still don't want them to climb if caught out though............... |
Still don't want them to climb if caught out though............... 1, Avoid IMC early, but if you get caught out 2. Try to reverse course with 180, but if that doesn't restore immediate VMC 3. Climb wings level to Safety Altitude Not a tricky concept to teach:ok: |
I'd say this is one of the eternal "one size doesn't fit all" situations.
There is an argument that says carry out the 180 turn then descend, rather than climb because that should put you back where you were, in VMC, rather than risk an unrehearsed climb to a safe altitude (it's only safe if you can get down again). My pre-planned option when taking off from a certain unlit night site with no weather "actual" information and hitting very low cloud was to keep the wings level, keep the speed under control and descend. I had to use it one dark night when the weather forecast was very wrong. We got out of the situation by carrying out a very low level circuit (less than 250' agl). Another aircraft, not a million miles away, hit the same low cloud a couple of hours later. The pilot tried to turn back, became disorientated and crashed, killing one occupant and seriously injuring himself and others. But... "If in doubt, chicken out" is the best advice. |
If you assume worst case and have to complete a full 180 deg rate 1 turn (whether it be level or not) - do you really want to spend a whole minute IMC below safety altitude covering a substantial area of real estate you can't see?
After many years of reverting from VFR to IFR, both planned and unplanned - the idea of that turn scares the bejeezus out of me. As I said before, the 180 works when you still have some ground reference and can 'pop' back out of it - ie you haven't waited too late (late but not too late) to make your decision. |
So far nobody has suggested what the LAPL holder should do. They have not even been taught an instrument turn!
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Only go flying on a CAVOK day perhaps:ok:
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That's why it can never be a case of "one size fits all" and "if in doubt, chicken out (early!)".
Plus, in a situation where you find yourself facing deteriorating weather, always bear in mind an escape route. If you've turned back through 180 degrees, you're over the same terrain you were two minutes ago. BUT if you've been scud running for a prolonged period at low altitude over an area where it was risky to be flying at in the first place, then I agree that your only option is to climb. Climbing into bad weather can also go very badly wrong: https://www.gov.uk/aaib-reports/pipe...-february-2007 |
That event shows how important decent planning and Met appreciation is.
Poor decision making to attempt VFR transit when the TAFS and METARs were unsuitable - when you get airborne and go IMC at 200' you have got something wrong. When you get into a situation where you are descending over water at twilight to try and get VMC beneath, you are a very long way from where you should have made a much better decision. Maybe this is what should be emphasised for LAPL and the like. |
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