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See where I’m going? The question is not whether there is a common cause, but at what level. If one was weather, and one was electronics, some will say that there’s no link; others will see no difference.
Language is a wonderful thing, isn’t it? Not just English - all of them have this in common!
Irrational cause and effect conclusions. Sure, they were both airplanes, duh! They had THAT in common. However, the SOURCE points of the events were DIFFERENT.
So what was the common link? All were airplanes? All flown by Pilots? All Cirrus? You spoke with him, so tell us why he pulled the CAPS? (I flew over the same area about 2 hours earlier)
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Free Flight Enterprises website says, “We are parachute systems specialists and we do custom sewing.” So it is possible they are a subcontractor to BRS; they have pictures of BRS chutes on their (rather spare) site.
Curt,
Thanks. I spoke with Mark Thomas, president of BRS. He confirmed that FFE is indeed a subcontractor - they put the BRS-designed 'chute together. Mark was a bit surprised, though, that anyone would characterize FFE as the supplier to Cirrus!
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Irrational cause and effect conclusions. Sure, they were both airplanes, duh! They had THAT in common. However, the SOURCE points of the events were DIFFERENT.
Bruce,
Thank you for emphasizing my point. [:)]
Scott, Matt & other CFIs: just when is it unsafe to maintain altitude in a mountain wave?
I had the experience a few weeks ago and noticed GS changes of +/- 20 kts. Given a TAS of about 170, and an indicated of about 150 +/-20, I did not feel that I was anyhwere near stall speed and maintained a comfortable margin of safety. To me the safest course of action was to keep the A/P on (ALT Hold), keep a close watch on it and the IAS and notify ATC. ATC was well aware and ‘enjoying’ watching myself and two other planes on front of me deal with the wave. In fact, i could ‘see’ the waves and the cloud tops ‘showed’ the waves.
I always caution my wife that there are few absolutes in flying. She is very black and white and likes things to be either GOOD or BAD. My argument of “Grey” fall on deaf or at least reluctant ears. Is this Mountain Wave/ autopilot advise one of these grey areas, or was I foolish?
Scott, I fly frequently to the southwest from the Washington DC area, which entails 3-4 hours over the Appalachians in my underpowered Warrior. I have encounted fairly severe turbulence (once rolling the plane more than 90 degrees), as well as the nonbreaking waves you refer to, when it is impossible to hold altitude. Of course, I try to get as much altitude as possible before going over the ridges. The truly severe turbulence and downwaves have occurred when the winds at altitude were in the 50-60 knot range. As a result of these experiences, I tend to avoid mountain flying when the winds are in that range or when it is IFR.
Is there a rule of thumb you have regarding expected turbulence or downdrafts for different wind speeds?? ( In my experience, I am perfectly comfortable when the winds don’t exceed 25-30 knots). Also, if one is unable to hold altitude in a downward wave, is there typically a floor, or bottom, at some level AGL to the downward wave when you could expect to stop descending? (In my experience, I’ve found that I usually transition from down drafts to equally strong updrafts, every four or five minutes…but have never ridden one down low enough to discover a floor). As I recall, my experiences have all been on the leeward side of ridges, but several thousand feet above ridge level.
Your insights appreciated!!
David Brandon
Washington DC
I tend to agree with letting the airspeed vary as long as the air is smooth, and ATC is informed. As an extreme, letting the airspeed decay to Vy, then lowering the nose to hold it there will keep the aircraft as high as possible - if that’s what’s desired. If the air is not smooth, using a higher airspeed and accepting a lower altitude is necessary. In this case, attitude and aircraft control become the first priority, closely followed by terrain planning and communicating with ATC.
If an altitude block is available, that may solve the problem, but in some places with a 16,000 MEA for example, there isn’t much room below anyway. Sometimes requesting and going lower to the MEA even if it is the “wrong way” will solve the problem by improving aircraft performance.
In IMC, having a moving map with terrain depiction is an emergency measure for going below the MOCA. (Yipes!)
But of course nothing beats good pre-flight planning to avoid waves beyond the aircraft’s capabilities.
John,
That is hilarious! [:D]
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To really appreciate the highly thoughtful accurate reporting by the Sun Sentinel, you really needed to see the headline on the print version of this story in this morning’s paper: "ENGINE WOES FORCE PILOT TO BAIL OUT AFTER TAKEOFF
Now Jeff is in REAL trouble. He thought yesterday was a bad day. Now he will get nailed by the FAA for parachuting without proper certifications!!! It must be true if it is in print!!!
Well Miami ch 7 was more careful tonight and just said undetermined causes.
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Also, if one is unable to hold altitude in a downward wave, is there typically a floor, or bottom, at some level AGL to the downward wave when you could expect to stop descending?
If the wave brings you below the height of the peaks, you risk entering the rotor. There you could find the most severe turbulence outside of a thunderstorm, well beyond the capabilities of your aircraft. Turn back before that!
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Also, if one is unable to hold altitude in a downward wave, is there typically a floor, or bottom, at some level AGL to the downward wave when you could expect to stop descending? (In my experience, I’ve found that I usually transition from down drafts to equally strong updrafts, every four or five minutes…but have never ridden one down low enough to discover a floor). As I recall, my experiences have all been on the leeward side of ridges, but several thousand feet above ridge level.
Dave,
It is a good question. See this post to Curt for an explanation.
If the wave brings you below the height of the peaks, you risk entering the rotor. There you could find the most severe turbulence outside of a thunderstorm, well beyond the capabilities of your aircraft. Turn back before that!
-Curt SR22 #457 formerly SR22 #44<<
Well, I can sure confirm that, having dropped once below ridge level to escape 60 knot headwinds over the Shenandoah value. That’s when the plane almost went inverted.
Your point is well taken. Put no faith in a floor to the downwaves, as things will only be worse down below. If one is not comfortable with the winds at altitude, it may be time to turn around.
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If the wave brings you below the height of the peaks, you risk entering the rotor. There you could find the most severe turbulence outside of a thunderstorm, well beyond the capabilities of your aircraft. Turn back before that!
Curt,
I believe there is still some confusion over breaking vs non-breaking waves. There are basically two types of mountain waves or lee waves: Turbulent (breaking) and non-turbulent (non-breaking). Here in the east, we experience more of the non-turbulent lee waves variety.
If I’m reading his post correctly, Dave was asking about the non-turbulent wave scenario which typically doesn’t have the same effect as the turbulent lee wave or rotor that you were referring to. You lose airspeed very rapidly and have a very difficult time maintaining altitude. Often the air is extremely smooth.
In general, here are some things to watch for. Pay attention to AIRMET Tango and SIGMETs that warn of mechanical turbulence. Also, clouds indicate rising air. If you are in a non-turbulent lee wave losing altitude or trying to maintain altitude you will stop losing altitude at the level where the clouds are below you (if any).
In these non-turbulent lee wave scenarios you normally have super-adiabatic lapse rates (unstable) in the lowest part of the atmosphere transitioning to a very stable atmosphere above the ridge line. As fast air is forced rapidly above the ridge, it encounters a stable atmosphere and begins to sink on the other side of the ridge (remember this is lots of air moving over the ridge). This up and down oscillation stays between the unstable layer below and the stable layer above, but can be felt to very high altitudes above the ridge line as can be seen in the attachment below.
Scott…you have exactly described the situation I faced when I was most concerned whether I’d make it. In fact, there was a solid cloud deck below me, tops about 4-5 thousand ft. I was at 7000 returning from Mississippi to DC, just east of most, but not all, of the ridges, with about 60 knot tailwind (from sw). I was at full power, best rate of climb (79 knots), and still sinking at least 500 ft/min. My concern was whether I would go into the clouds, with mountains still below me. If I had had your explanation then (or even thought about why the cloud tops seemed stable), I expect my pants would have been much drier on that trip! 
Thanks!
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Scott…you have exactly described the situation I faced when I was most concerned whether I’d make it. In fact, there was a solid cloud deck below me, tops about 4-5 thousand ft. I was at 7000 returning from Mississippi to DC, just east of most, but not all, of the ridges, with about 60 knot tailwind (from sw). I was at full power, best rate of climb (79 knots), and still sinking at least 500 ft/min. My concern was whether I would go into the clouds, with mountains still below me. If I had had your explanation then (or even thought about why the cloud tops seemed stable), I expect my pants would have been much drier on that trip!
Thanks!
Dave,
I’m quite familiar with that route and with the mountain waves you experienced – been there done that. The clouds are good indicators of rising air. However, on one of my trips (headed south along this route) I hit a huge wave while I was at 8000 ft and ended up holding altitude at 7,200 ft while at Vy and at full power in my Turbo Arrow. I was IFR and the MEAs along this route are at 6000 ft. I estimated the cloud tops to be at 6000 ft and the temperature to the surface was below freezing (yep, icing was a possibility). Going into the clouds wasn’t a choice that time for me.
It was so smooth in the wave that I could have easily been lulled to sleep. Yeah right [;)].
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So what was the common link? All were airplanes? All flown by Pilots? All Cirrus? You spoke with him, so tell us why he pulled the CAPS? (I flew over the same area about 2 hours earlier)
Denis,
I suspect I’ve failed to make my point clearly enough.
Let me try again: You believe there was no common link. I believe that, too. But, if someone wants to find a common link, they will find one.
This pilot recognized a perceived or actual, imminent or current, loss of control - an appropriate reason to deploy the CAPS, IMHO, without regard to what lead up to that situation. The root cause is something that may be uncovered by an appropriate investigation; I won’t guess at it.
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Denis,
I suspect I’ve failed to make my point clearly enough.
Let me try again: You believe there was no common link. I believe that, too.
So the common link was … there was no common link. Most ingenious.
One common link with the BRS is that we will eventually hear the pilot’s side of the story and hopefully learn valuable insight we all can benefit from - something that rarely occurs in these type of cases without a BRS.
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This pilot recognized a perceived or actual, imminent or current, loss of control - an appropriate reason to deploy the CAPS, IMHO, without regard to what lead up to that situation. The root cause is something that may be uncovered by an appropriate investigation; I won’t guess at it.
Mike that is a very important point.
At the time any pilot senses that they have lost control of the airplane and are not absolutely confident of their ability to recover, then that is absolutely the right time to activate the CAPS. Saving your own life, that of your passengers, and potentially more on the ground are the most important things to consider at that moment.
I have heard about (I certainly wouldn’t read any other type clubs bulletin boards[;)]) threads on other aviation sites about how the pilots should not have gotten into those situations, should have been able to recover, or without the extra weight of the CAPS system may not have been in that exact situation. (Quite frankly, none of us were there and we will probably never know for sure exactly what happened and why.) But all of that is pure speculation and IMHO rationalization, but nonetheless, totally beside the point. At those moments two pilots had an out that saved the lives of 5 people. Whether loss of control was caused by mechanical problems, pilot error, bad WX, poor planning, or a myriad of other possibilities is not the issue. We are all way to prone to those possibilities and to ignore them is short sighted. Today, 5 people are alive precisely because they had one extra piece of safety equipment.