10,000 Feet for RAA - Uses and Threats

[Guest davidh10]

Well, if we believe the tea leaves, our 5,000' ceiling for normal operations is about to be lifted, meaning that 10,000' will be the new limitation.

 

If you stop to think about it however, there are new threats that present themselves and require some conscious thought and planning before just sailing up to 10,000'. With this in mind, I thought I'd start this thread to enlist the knowledge and experience around the forum to help everyone to understand the advantages, but also the threats that this new privilege encompasses.

 

Will you use it? If so, to what purpose?

 

What threat / error management will you use specifically above the current 5,000' normal operations limit.

 

Some of my thoughts...

 

I contemplate using it occasionally, but only for specific reasons, such as:-

 

• Being able to avoid turbulence at lower altitudes.
   
   
  
• Utilising a faster tail wind (on useful occasions).
   
   
  
• Being able to fly over appropriate cloud coverage with the required clearance from cloud.
   
   
  

 

 

I may even be able to get on top of all the smoke from farm paddock burns that is happening at present. It was like first day of Autumn and someone flicked the "smoke switch". Last night I could't clearly see the aerodrome from five miles out and all I could see of the other aircraft up with me, at four miles separation, was his landing light through the smoke.

 

So what are the threats that we don't have or are less below 5,000':-

 

• Hypoxia. Depending on your state of health, this may set in as low as 8,000'. Not something you want to discover without another pilot in the aircraft. This article provides further information.
   
   
  
• CTA. As RAA pilots we have generally put out of our mind, any CTA above 5,000' as it didn't matter, but now you have to look at you VNC or VTC and consciously check. Where I am, we have "E LL 8500" over part of the local area. Next step up, not an issue as it is over 10,000'.
   
   
  
• Aircraft overflying are unlikely to give radio calls on the CTAF, as they will be high enough to not interfere with AD operations in the local area.
   
   
  
• Larger inbound aircraft may be descending through these altitudes at 20 to 30nm out from the aerodrome and may not yet have made a CTAF call (also see IFR flights below).
   
   
  
• VHF Radio is required above 5,000' even if there is no requirement below 5,000' in at vicinity.
   
   
  
• IFR flights in Class G airspace are more likely to be above 5,000' and don't require an ATC clearance, so may be silent on the radio and head down in the cockpit. You will hear the ones that communicate with ATC if you monitor CENTRE as well as CTAF.
   
   
  
• Transition Layer issues with altitude datum change and accuracy. Up to 10,000' aircraft operate their altimeter based on area or local QNH (barometric pressure at sea level), however aircraft above the transition layer operate on a reference atmosphere with fixed QNH at 1013.2 HP.
   
  In theory, nobody should be cruising between 10,000' and 11,000' (FL110). In times of low barometric pressure the transition layer extends up to FL125. While aircraft are supposed to change their altimeter to local or area QNH before descending through the transition layer, like everyone else pilots are human.
   
   
  
• RAA pilots operating below the transition layer and hearing altitude reports of aircraft above it, but descending, need to be aware of the difference caused by the different datums being used and thus the actual vertical separation versus just the difference between the two altimeter readings. Obviously the difference depends on the barometric pressure at the time.
   
   
  

 

 

[*]Pilots of fast aircraft above 5,000' are probably not expecting to encounter low performance aircraft in the 5'000 to 10,000' range.

 

[*]Stronger winds than we may be used to at up to 5,000'. Is it within the aircraft and pilot capabilities on the day? With this, the possibility of more layers of air moving at different speeds in different directions and the resulting turbulence between layers.

 

Ok, that's my thoughts... What have I missed? Have I got something wrong?

 

*Edit 4th Aug. 2011 - Added link to hypoxia article and point about 20nm inbound aircraft.

 

 

[Guest burbles1]

ADS-B coverage improves with altitude. Have a look at the maps at http://www.airservicesaustralia.com/projectsservices/projects/adsb/coverage.asp and the differences between 5000 and 10,000 ft. RA-Aus has opened up its members to being more likely candidates for mandatory ADS-B and Mode C transponder equipment.

 

 

[Guest Crezzi]

What have I missed?

The cruising level must be appropriate for the magnetic track

 

Cheers

 

John

 

 

[slartibartfast]

Well covered David. The decreased pressure can also get you in other ways. I was once at nearly 10,000' (in a part of the country where you would need a tunnel to fly at 5000') and a loud explosion really focussed my attention. It took a minute to work out that the packet of chips in my flight bag had spontaneously opened.

 

The best thing about the increased height will be the freedom to choose 5,500' when travelling east and 3,500' is too low.

 

The turbulence avoidance is great too.

 

 

[eastmeg2]

600kg . . . 10,000ft . . . in the next 8 weeks.

 

I wonder if Mick will put on a Santa costume to deliver the good news at Natfly.

 

On the serious side though. Many of us will need to become more proficient at knowing the Area Frequency where we're flying and making the approriate calls when above 5,000ft.

 

Cheers,

 

Glen

 

 

[Guest davidh10]

ADS-B coverage improves with altitude. Have a look at the maps at http://www.airservicesaustralia.com/projectsservices/projects/adsb/coverage.asp and the differences between 5000 and 10,000 ft. RA-Aus has opened up its members to being more likely candidates for mandatory ADS-B and Mode C transponder equipment.

Maybe eventually, but at present isn't the ADSB requirement only compulsory over FL200?

It may strengthen the case for having a Mode C Transponder, but ADSB does not really add anything useful, either for ATC or other aircraft with TCAS. Not that usefulness is necessarily a key decision criteria :-(

 

{For those who want to know more about or better understand ADSB, there's an excellent podcast interview with Bill Hamilton by Bas Sheffers on Plane Crazy Down Under} You will recognise both these names as forum members. Be aware that if you choose to download the podcast, it is about 70MB.

 

 

[bones]

600kg . . . 10,000ft . . . in the next 8 weeks.I wonder if Mick will put on a Santa costume to deliver the good news at Natfly.

 

On the serious side though. Many of us will need to become more proficient at knowing the Area Frequency where we're flying and making the approriate calls when above 5,000ft.

 

Cheers,

 

Glen

Righto up here where i am there is mainly 1 ctaf freg, what are the differences and benifits of using the area freg over the local ctaf freg?

 

Eg. if i have this right :) FIA is 120.55 and CTAF is 126.7 here at YCHT, and a further out at YJLC some 700km away the CTAF is still 126.7 but FIA is 123.95.

 

So what info(i never bothered with area freg) do you get from area that you wouldnt get from CTAF?

 

I listen to a/c landing calls all around the area on CTAF, so if i were flying into one of these airports, i would know whats around anyway.

 

 

[Guest burbles1]

Maybe eventually, but at present isn't the ADSB requirement only compulsory over FL200?

Nobody wants ADS-B, but if you read CASA's discussion paper you'd think that it is a foregone conclusion for rec aircraft in Class G. I certainly gave a vehement response against it.

[Guernsey]

I believe that 10,000 feet will be very useful for Jabiru engined aircraft because they will have a much safer gliding distance when the engine stops:happy dance:

 

Yes our Morgan will have a Jab engine.

 

 

[Ultralights]

dont forget with flight above 5000, your "proximity" to a CTAF and aircraft operating in and out of it, will be quite large. a nice example is a SAAB 340, or Dash 8, descending into a CTAF, they will be descending through the 10,000 to 5000 ft area up to 30 Miles out.

 

Above 5000 i always monitor the appropriate Centre frequency and also CTAF when within 30 Miles. (if more than one, then the one with known RPT traffic),

 

you can be transiting past a CTAF, 20 miles from it, and you will be in conflict with a Departing Dash 8 as its on climb to it cruising flight level in your direction. (eg, a Dash 8 departing Dubbo for sydney, will be climbing your way if you are tracking south, but 20 miles to the south east of the field.

 

my biggest safety concern is low level IFR betwen 5 and 10,000ft, so with this in mind, dont plan on following a busy IFR airway between waypoints

 

 

[Admin]

Guys, we need to wait and see what "exactly" is handed down

 

 

[Robert]

Hi All

 

All this is great but what worries me is how long before we are put into the avaition medical system (bi annual aviation medicals)

 

I think a line has to be drawn in the sand somewhere with RAAus saying this is as far as we want to go. If a person wants more than Reg your aircraft VH

 

Cheers

 

 

[FlyingVizsla]

what are the differences and benifits of using the area freg over the local ctaf freg?

Bones,

 

When you get outside the vicinity of an airport the talk is on the Area Frequency. You need to do some mental maps as the IFR aircraft ask Air Traffic Control about traffic on their route and operators do some separation negotiation. Also some useful stuff like QNH, weather alerts etc. Chatter like - one aircraft doing a scenic along the coast, not above 3,000 talking to a chopper who is doing beach filming near their track, the progress of IFR flights. I was on a long outback flight when I heard a higher performance IFR doing the same track as we were, calculated his ETA and pointed out the shadow going over us 2,000ft above - the passenger was most impressed, also made sure I WAS 2,000ft below, because ATC don't provide separation from VFR traffic. Can be disconcerting too - had a fellow pilot as passenger, and as usual with me hit a headwind; cars were passing us, aircraft at fligh levels were taking off from where we left ages ago, landing where we were going and got to the next destination and we were still chugging. All I could hear from the RH seat was complaints against the world in general, weather in particular and "I could walk faster.." The difference with Area Frequency is the guy sitting in the Brisbane Centre at his radar / computer screen liaising back & forth with the IFR traffic in the area. If you get into strife he is the best one to talk to as they can alert rescue services, relay messages, help you get out of the clag, get unlost, get someone to talk you down etc. They also talk plane to plane, usually to sort themselves out when they are outside an airstrip (not inside a CTAF). You can listen in real time to ATC / Area over the internet, or for real on the VHF.

 

Sue

 

PS helps to know the Area Frequency - Don't know if it is still there - I landed at Jamestown(?) SA and on the building with the toilets was a number pad with the plaque

 

"If perchance you want to pee,

 

Dial the Area Frequency." Punch those numbers in and "Hey Presto" we were IN.

 

 

[Guest davidh10]

Ian; I guess we are just assuming that the delivery will meet the expectations that have been set over time. As with all things in life, we will have to adapt to whatever reality is revealed.

 

The RAA CEO has reviewed CASA's proposed rule changes and not modified the language foreshadowing the change, unlike the other two modifications.s which will have qualifications.

 

Robert; There are a lot who share your concern. I believe it has been addressed by the statement that the RAA was persuing incremental privilege increases. In other words, any new restriction or qualification would be attached to that privilege, and not be a blanket requirement.

 

 

[Tomo]

Legalizing it will be nice...

 

I guess I've operated above 5000ft quite regularly at times, as I've done gliding, and we often climb to 9500ft on a good day. To cross the ranges you have to go above 5000ft as well.

 

Being sure you use the correct compass heading/height configuration, and monitor Area freq. Having a transponder would certainly be a good plan as well.

 

Just my 2 cents

 

 

[kaz3g]

WAC's, VNC's and VTC's may not show you all of the info you need for a safe flight. I suggest you should also have the relevant TAC which will help you identify and steer clear of some of the R zones not shown on the others such as R251A and R252 north of Whyalla, SA. TAC's also show you the IFR routes that may be populated with people who aren't expecting you, especially if they can't detect you on their collision alert screens.

 

If VFR above 5000, it's good manners to give an all stations to let traffic and flight service know what you are doing and again when you are leaving. VFR levels are mandatory above 5000.

 

kaz

 

 

[facthunter]

The Outside Air Temperature, will be 20 degrees colder than at MSL on any normal day. Watch out for icing. Your airspeed will significantly under read because of density altitude considerations. This is important IF you descend at a high speed. Your actual speed may cause you to be over VNE. Your indicated stall speed will not change but since power is down and prop efficiency and lift are down, you will be closer to your SERVICE ceiling, or ABSOLUTE ceiling and will have less margin above the stall than when lower down. In fact some aircraft will not be able to get to 10,000 feet at all . IF you encounter turbulence it may require an increase in indicated airspeed to maintain a safe margin above the stall. The only way to achieve this will be to descend. being at 10,000 feet does not guarantee a smooth flight or the absence of turbulence. It will help you to get above some of the annoying convective turbulence associated with flying inland in summer, as it may enable you to get above the "inversion layer", but that can be above 10,000 feet on a hot day in the afternoon when temperatures peak. Nev

 

 

[Spriteah]

airspeed will significantly under read because of density altitude considerations. This is important IF you descend at a high speed. Your actual speed may cause you to be over VNE.

 

This is an interesting one. Now the forces on the aircraft at higher altitude will be less due to air density being lower. So "can we exceed the VNE when the indicated is under it?" Any smarties out there that can answer that?

 

Jim

 

 

[rgmwa]

airspeed will significantly under read because of density altitude considerations. This is important IF you descend at a high speed. Your actual speed may cause you to be over VNE.This is an interesting one. Now the forces on the aircraft at higher altitude will be less due to air density being lower. So "can we exceed the VNE when the indicated is under it?" Any smarties out there that can answer that?

 

Jim

Vne is a function of the velocity of the air molecules relative to the aircraft, not the density of the molecules. Consequently, because the indicated airspeed is reading low due to the lower air density at altitude, you could exceed Vne without realising it (until part of your plane falls off).

 

rgmwa

 

 

[motzartmerv]

Its a good point that nev raised, and an interesting topic on its own. Safice to say that the ASI works off dynamic pressure, basically, how many air molecules are squeezing into the pitot. As we all know, with a gain in altitude the density of the air reduces, so to have the ASI needle in the same place the aircraft must be travelling faster, this gives us the difference between True airspeed and indicated air speed.

 

VNE is Velocity never exceed, Not ANE, airspeed never exceed.

 

Design limitations are worked out on velocity, or to put it another way, how much energy is in the system. At these higher speeds (true, not indicated) there is more energy in the system. It is this energy that in the right circumstances can start to cause flutter and other phenomena, even though the ASI needle is well within the green arc.

 

 

[rgmwa]

Flying high and fast

 

This article about the implications of exceeding Vne may be of interest.

 

http://www.vansaircraft.com/pdf/hp_limts.pdf

 

rgmwa

 

 

[eastmeg2]

Good article,

 

Thinking how this could apply to trikes even though the article is about 3 axis machines with a much greater speed range.

 

I know some trike pilots pull the bar in for more speed in rough air to increase their roll control authority and reduce the effort they have to put in to keep wings level, but, I've thought about the other side of the coin where we need to consider the gust loadings on the wing being greater at higher air speeds, so tend to fly my Streak3 at no more than about 60kts IAS (VNE = 85kts IAS) knots in really rough air, rather than pushing (pulling) it over 70 kts.

 

Cheers,

 

Glen

 

 

[Yenn]

I thought that the hemispherical levels applied above 3000' not 5000'

 

 

[Guest Crezzi]

I thought that the hemispherical levels applied above 3000' not 5000'

You might be getting it confused with the different Class-G VMC minima above/below 3000' ?

 

 

[djpacro]

Some comments related to certified airplanes.

 

Designers must take into account all the real limitations when certifying their aeroplane and defining the airspeeds in the Flight Manual. If a single VNE is declared in IAS then that is valid up to all altitudes achieveable (or certified). True that the highest TAS is likely to be the most critical for flutter so the minimum margins in that case would occur at VNE at the highest altitude.

 

Some aircraft types declare lower VNE (IAS or maybe CAS) for higher altitudes.

 

Regardless, if the certification substantiating tests and analyses are done correctly a pilot should be able to safely operate to the specified indicated VNE to all altitudes (per flight manual limitations - smooth air etc).

 

Problems have arisen with modifications increasing the engine power where the original certification is no longer valid. eg a higher altitude is achievable than originally determined - it may not have been specified in the Flight Manual so not obvious. In this situation the achievable max TAS is beyond the value previously determined by the designer. Should be OK if the modification is properly certified.

 

Sometimes things slip through, especially with self certification. I recall reading about some flutter work for one certified airplane being simply an estimate. This is a long way short of the normal proof of freedom from flutter within the flight envelope (both airspeed and altitude envelopes). That is proof that the minimum flutter speed is whatever percentage (20 or is it 25, can't remember) above the maximum demonstrated in flight speed during certification tests. VNE is normally set at 10% lower than the maximum speed flown in tests - noting that the critical condition is that combination of max IAS and max altitude.

 

i.e. pilots shouldn't need to second guess the designer - just stay within flight manual limitations.