6 minute markers and the 1 in 60 rule explained

[motzartmerv]

Lowest safe altitude is a pivotal part of vfr flight planning.

 

Everyone has different ideas, but i tend use the highest spot elevation within 5 miles either side of track+ 500 feet. Some people I know add 1000 ft.

 

Its crucially important, particularly around control steps and tiger country. When doing the plan if cta steps or even vfr minima (cloud clearance) would force the planned height close to or below LASLT (aswell as trying to remain at the proper atmospheric cruise level) then another route must be taken.

 

Also, i think that if unforeseen wx has you dodging clouds, or even scud running(not a good idea) having a number to work on ,ie LSALT for the area is the go.It is not something you will want to be looking up on a map while flying yourself out of the hole.

 

I must stress that LSALT is not Lowest SAFE height to fly at. I use 500 ft because then you know you will always be legal, but it would be very unadvisable to fly at 500 ft agl for any length of time.I think its designed as a stop height, i cannot go any lower than LSALT due to terrain clearance, its not the lowest safe height for me to fly around at.

 

I should add that if the spot elevation is also a built up area then it must be 1000ft minimum. (not sure of the rule on that one)

 

cheers.

 

 

[deadstick]

LSALT or lowest safe altitude for VFR flight is one of those things that is great to have for a warm and fuzzy, I run a quick check for all VFR nav purely for those one offs (if I go inadvertant IMC) and also the unknown transmission towers that may pop up I take a scan of the topography 5 miles either side of track and add 1300ft just in case someone put a new tower up and didn't tell anyone. So if flying along and suddenly I am in cloud a quick scan of my knee pad/ map gives me my LSALT and straight into the climb I go. Have only needed it at night so far but its one of those things for VFR if I dont plan it I will need it.... LOL

 

Also the proceedure for calculating LSALT, navaid to navaid, navaid to AD, and no Navaid is in AIP...

 

 

[sfGnome]

I know that the experienced pilots will already know this, but here's a little cautionary tale for those like me with lots still to learn. Flying north one day into a stiff northerly and trying to keep to the 3500' altitude suitable for my heading, I had to pass over an east-west range with a clearance of only 500'. That's ok, thinks I. It's only a ridge, and I'll have plenty of hight (AGL) on either side of the ridge. Wrong, wrong, wrong. On the southern side of an east-west ridge with a strong northerly blowing over it will be a nice big sink, and I proceeded to lose altitude at an alarming rate as I approached the hills. Full throttle and a best angle climb recovered the situation, but it's not a situation that I want to be in again. I think that from now on, I'll treat the 'correct' cruise altitudes as the guide that they are (below 5000) rather than treating them as the rule that I was. Definitely a case where LSALT was not a safe altitude at all.

 

 

[facthunter]

Moving along a bit then..

 

Thanks for the response, I did say VFR, where I should have said in VMC. (Visual Meteorological Conditions) which are defined and should be familiar to us all. Now I am not trying to set anyone up.

 

We are going along and it appears we cannot procede along our track to our planned destination.( Whatever reason, wee stop, or to take on more fuel or due weather etc. We can divert to fix this.

 

Would you be able or would it be wise to (as well as checking fuel and track) to take the time to derive the NEW LSALT. for the diversion leg?. I would suggest that maintaining a good lookout and monitoring your progress would be more productive. In fact you could conduct the whole diversion below LSALT and shouldn't be able to be ctiticised/failed for doing so.

 

I am actually saying that the LSALT has little to do with anything when in VMC.

 

IF you happen to go into IMC, (well you shouldn't have, should you) it might allow you to think that You are OK for a while at that level, but you have bigger problems looming.

 

Can I get some more views? Nev

 

 

[Guest davidh10]

...On the southern side of an east-west ridge with a strong northerly blowing over it will be a nice big sink,...

During my Nav training, I found a couple of excellent "Mountain Flying" sites that talk about flying techniques around mountains and in canyons.

 

I'm pretty sure this was the one on Mountain Flying and this one on Canyon Flying.

 

You need to understand not only standing waves, mountain waves, but also rotor.

 

A Lenticular cloud over a mountain or ridge is a dead give away of a mountain wave, but they aren't always present and rotor mostly has to be imagined, as it is seldom seen. That's why it is so dangerous.

 

 

[farri]

A little off topic,I know....But

 

In the types of aircraft that we fly,in my opinion,good navigation is not as much about the method we use or how we do it as it is about getting to where we want to go, efectivally and safely.

 

You are never lost if you know where you are, relative to where you want to go and know how to get there.

 

Cheers,

 

Frank.........K.I.S.

 

 

[motzartmerv]

Nev, so the answer to your own question is: not much..... your a crafty bugga..:)

 

 

[facthunter]

Results.

 

Thanks Merv. I think it's a hang over from the days when all flight plans were done on the one pro forma.

 

You ticked VFR/IFR in the square, back then.

 

I genuinely like to get peoples opinions and like to get us thinking. We need to test the validity of a lot of things, not just do them because someone says you should.

 

Sorry for taking over your thread. (I realised it later.) Nev

 

 

[motzartmerv]

No worries. Its all good discussion. ;)

 

 

[foxy]

hey guys,

 

my added opinion, which im sure plenty of you are aware of, and use, is that through the planning stage, working out which altitude to fly at......find the LSALT, as Motz said, height of highest terrain, then plus 500ft, THEN, take that up to the nearest odd or even thousand feet, whichever for the direction of heading, then add the 500ft addition.

 

adding that extra thousand or so feet to the LSALT as the planned flight altitude, gives you plenty of allowance for whatever.

 

as always...err on the side of caution! :big_grin:

 

 

[motzartmerv]

And yet it is on the Airsevices VFR flight plan form. http://www.airservicesaustralia.com/flightbriefing/adfn/docs/adfnformbackpt.pdf

 

And I would beg to differ, it is part of a standard VFR flight plan, as others have stated. Ive read through the post's again and can't find anyone saying its the hight of terrain.

 

Nev's question was specific to VFR flight planning. Not IFR.

 

 

[flightygirl]

can i ask why you wouldnt use LSALT? surely it is worthwhile doing regardless of whether you are IFR or VFR?

 

 

[motzartmerv]

I never said it was a legal requirement, but a standard part of VFR flight planning. If you don't want to spend the time to calc it then don't. But don't disagree with those who do, the more information the better i reckon. Would you disagree with that?

 

 

[djpacro]

My opinion: day VFR requires different considerations of one's personal minimum height for a particular section of a route than the simple IFR (or night VFR) process of elevation plus. eg what are the options for a suitable forced landing area? More height is good over "tiger" country -going around it is my preferred option but not always feasible.

 

For example, going through the Glenburn gap just north of Lilydale the spot height is 2100 ft along my route and I don't care about the spot heights of 2700 ft which are 2 nm to the east as I can see them and I'm not going there. My main concern is the scarcity of open areas to put down on if I need to - lots of forest and steep hills.

 

If you like, the LSALT column seems like a good place to note that, separate from the planned cruise altitude.

 

 

[foxy]

ok. just one question here.

 

i may be a bit naive, being only reasonably new to the entire venture ( and by new i mean only two and a half years, including my training and instructor rating), but seriously...aviation is a sport than can and has very easily killed many good people. The entire emphasis on any part of flying should be on safety. flight planning included. lets consider those who havent done many nav's, as well as those who have done thousands of hours of them. there is a lowest safe minimum for all of us.

 

there was a publication put out, that has the statistics in it, showing that poor flight planning was what had killed the majority of the people involved....regardless of experience.

 

wouldnt we, as both private aviators and instructors, want to keep everyone alive??

 

cfi...ur an instructor rite?? do you not aim to teach your students the safest option for everything???id hope you would, but im kinda lacking in that belief from the last few of your posts here. its sounding to me a little too..."cowboy"ish.

 

why on earth WOULDNT you teach an LSALT???

 

dj...you said..For example, going through the Glenburn gap just north of Lilydale the spot height is 2100 ft along my route and I don't care about the spot heights of 2700 ft which are 2 nm to the east as I can see them and I'm not going there.

 

this would bring in the correspondence from this and other threads....you mite not WANT to go two miles off course...but what happens if you inadvertently do??

 

youve planned for your lowest safe altitude to be 600ft above where you now are....now what are you going to do? have you planned the extra fuel for the climb to keep you away from that terrain?? (i realise that it may be minimal fuel needed, but still...was it planned for?)

 

lets not forget that this is a thread for students to ask questions and get 'correct' information. they are wanting, like all of us, i hope, to have a LONG, and SAFE life of aviation.

 

put things in prospective....lets think about total safety!

 

 

[motzartmerv]

Yes David, i believe thats what we are all saying. ANY propper flightplan should involve it.

 

 

[rgmwa]

For what it's worth, I was never required to fill in the LSALT column during my PPL (VFR) nav training, but was very definitely required to review and be aware of the terrain and other features along and adjacent to my planned route, and to select my planned altitude accordingly.

 

By the way Motz, I'd like to print off a copy of your notes if that's OK, but my plain old Microsoft printer thinks that your notes have been published in some exotic format that it doesn't recognise. Any chance of uploading a microsoft friendly version? Or is it just my printer?

 

rgmwa

 

 

[farri]

Lsalt???

 

To me,most of the discussion appears to be about theory and technicalities rather than safety.

 

I go back again to the reality of the types of RAA aircraft that most RAA pilots fly and the engines that power these AC and bearing in mind the regulations, put simply, Lowest Safe Altitude, (LSAT),should be , " The height that will keep you within Gliding Distance To A Safe Landing Area"

 

Every pilot chooses their own route,therefore,their own level of safety.

 

Frank.

 

 

[Guest davidh10]

I've been lurking for a bit, but thought I'd add something that hasn't been mentioned yet..

 

Does anyone take wind into consideration when calculating "LSALT"... Mmm Thought not. Suppose on your track, you have chosen to fly less than 2,000' above a ridge and you have a 20kn or stronger wind headed at you, roughly perpendicular to the ridge.

 

Wouldn't that somewhat invalidate the "S" in "LSALT".

 

Of course we all know that the wind direction and strength obtained from the Area Forecast, upon which you plan, is quite often at significant variance to local conditions, so how useful is LSALT in recreational flying?

 

Isn't it then better in VFR to just be aware of the height of terrain along and close to track. Take it into account for selecting planned track altitudes, but be aware of the surrounding terrain, and wind so you can make in-the-air decisions on what is a safe minimum altitude for any part of the track?

 

You may even choose to fly below LSALT, when flying VMC and maintaining VFR clearances, when and where it is safe to do so! Indeed, if you were not to do so it would be impossible to land, at say, Mount Beauty (which for anyone not familiar, is at the end of a dead-end valley varying in width between about 3nm and 5nm between 2,000' AGL mountains).

 

To me, this makes the formal definition and use of LSALT somewhat irrelevant to VFR flight, albeit rather important to IFR in IMC.

 

 

[facthunter]

Comment.

 

That is my point exactly. VMC is defined so that you SEE where you are going.. You often fly well below the tops of mountains that are fairly close to you. How would you land at Cairns and many other places. The wind effect is more important than the terrain clearance factor. Night VMC... another situation entirely. You can't see when there is no light. IMC you can't see because of the MC. Nev

 

 

[djpacro]

ok. just one question here. i may be a bit naive, being only reasonably new to the entire venture

As I said in the other place, I'm happy to listen to advice from anyone. (However as our friend said, I may not take that advice.)

 

wouldnt we, as both private aviators and instructors, want to keep everyone alive??

That's one question. I'll leave that to others to answer.

 

cfi...ur an instructor rite??

Two questions - I'll let See If I Care respond to this one.

 

why on earth WOULDNT you teach an LSALT???

That is three questions. As others have said - LSALT is not appropriate for day VFR. I used the term personal minimum height and I took care not to offer any general advice on a number for it. A variety of factors will come into one's own personal minimum - from ego (unfortunately); weather at the time; local knowledge (vs a stranger to the area) etc etc - feel free to add to the list.

 

dj...you said..For example, going through the Glenburn gap just north of Lilydale the spot height is 2100 ft along my route and I don't care about the spot heights of 2700 ft which are 2 nm to the east as I can see them and I'm not going there.this would bring in the correspondence from this and other threads....you mite not WANT to go two miles off course...but what happens if you inadvertently do??

That is four questions.If one is going to fly through a gap in a moutain ridge then one needs to fly through the gap, not beside it. Others have commented on a similar situation but I'll expand on that below.

 

youve planned for your lowest safe altitude to be 600ft below where you now are....now what are you going to do?

That is five questions.Why do you assume that my personal minimum altitude is 600 ft less than where I am now? You can see that gap from fifty miles away (if you can't then the weather is such that you should choose a different route). By whatever means of navigation I choose, I will fly to the gap. The gap is about 8 nm wide - we can fly over it quite safely at our own personal minimum height with a beady eye on adjacent high ground to ensure that the high ground does indeed remain adjacent to us. For that gap, the most important criterion is to have enough height to get to a suitable area for a forced landing - I said that I wouldn't declare my own view on a number but I will suggest that it is a very long way above 2700 ft. i.e. very much higher than any of the preceding guidance on calculating a LSALT.

 

have you planned the extra fuel for the climb to keep you away from that terrain?? (i realise that it may be minimal fuel needed, but still...was it planned for?)

That is six questions.Yes indeed.

 

lets not forget that this is a thread for students to ask questions and get 'correct' information. they are wanting, like all of us, i hope, to have a LONG, and SAFE life of aviation.put things in prospective....lets think about total safety!

Not a question but worth repeating. The question is - who decides what is "correct" information? Not me.Consider my typical flight where I'd cross the mountains at Glenburn, say a flight from Moorabbin to Temora via Yarrawonga.

 

After departure from Moorabbin the gap at Glenburn is quite clearly visible - not going direct as I want to avoid the inbound reporting point at the Academy and avoid Lilydale due to their parachuting operations. I plan via Coldstream.

 

On the way to Coldstream there's a big mountain with TV towers on top to a height of 2600 ft only 2 nm to the right of track. I won't be any higher than 2500 ft as that's the control zone lower limit there. What is my personal minimum altitude on that leg? As I said, I won't offer a figure except to suggest that it is quite safe to fly between Moorabbin and Coldstream somewhat lower than 2500 ft. Keep an eye out to ensure that the mountain on the right stays on the right.

 

Glenburn gap is clearly visible - 8 nm wide between one spot height of 2200 ft and 2700 ft - clearly easy to maintain separation from those peaks and maintain 500+ ft terrain clearance while crossing the gap. What is my personal minimum altitude? As above, it is very much higher.

 

The concern is the miserable opportunity to walk away from a forced landing. The control zone lower limit is 4500 ft so you could always get a clearance to climb into controlled airspace if you don't want to worry too much about accuracy of track right at that point.

 

Below 4500 ft you must ensure that you cross the mountains on track.

 

Most local PPL students get to use Glenburn on a nav and all would be familiar with the Kilmore gap. On this hypothetical day the cloud base is not much more than 2500 ft - average for Melbourne - and doesn't allow me to cross Glenburn at my personal minimum. Let's go with Plan B.

 

The Kilmore Gap. Lower terrain than Glenburn and more inviting for a forced landing - plenty of choices. Personal minimum altitude through this 7 nm distance along track? I wouldn't argue with the earlier guidance on LSALT except to add another consideration. One important factor is whether there is clear indication of improving weather there plus good weather beyond. Trouble with hills is that cloud often hangs around long after the Melbourne airfields are CAVOK. Sit on the ground at home until the actual weather report confirms you have the necessary cloud base. If it is improving then I'll start. If it is deteriorating I'll leave the aeroplane in the hangar and return another day.

 

Am I allowed to give a plug to a book by a local author?

 

"A Pilot's Guide to Safe Flying" by Sander Vandeth. Especially the page on personal minimums:

 

• Is this flight within my personal minimums?
   
   
  
• Have I considered all the risk factors?
   
   
  
• Have I allowed margins of safety commensurate with my knowledge, experience and proficiency?
   
   
  

 

 

 

 

[deadstick]

My own LSALT calcs are mainly for inadvertant IMC, I use the last step of terrain + 500ft as you know that last gradient mark could go up 500, then add on height of a transmission tower. If IMC this is now my lowest safe altitude before I could CFIT. Also Mandatory for night VFR you must know how low you can go before CFIT, I mainly use it in VFR flight for a warm and fuzzy should it all go pear shaped and I end up in the soup I will be safe from terrain above this height. The biggest mistake people make is not factoring in the height of a mast which could end your day quick smart and in a hurry!