Know It All…Or Not

If I have to repair this in flight, something is beyond horribly wrong.

If I have to repair this in flight, something is beyond horribly wrong.

I punched a fist of joy into the air upon reading Bruce Landsberg’s recent editorial in the February 2014 AOPA Pilot magazine. He addressed the topic of useless knowledge being taught rather than critical overall concepts. I’ve been saying this very same thing for years, but since I don’t have a type rating in the Saturn V, I’m viewed as a dangerous menace to the national airspace system. Thankfully, his article lends credence to my stance that we often focus on useless data in aviation that is of little practical or emergency use. We should be looking at the big picture items with a lot more interest rather than the little details that only impress other pilots or examiners.

While I’d love to claim credit for being a maverick as it relates to the idea of not needing to know everything there is to know about an aircraft, NATOPS was leading the way with this mindset years ago. Anyone who has flown in the US Navy knows that the manuals for aircraft are purposely designed to exclude excess systems information. The only things that are included are things that the pilot either has control over, or any system that can cause a hazard to continued flight (and how that hazard will manifest). The reason is simple: mechanics fix airplanes and pilots fly them. This division of labor is present even in civilian aviation where the FAA makes it a point to tell pilots that save for a few preventative measures; they are not allowed to be a mechanic on their airplane.

I believe this focus on knowing every system in detail is a holdover from the good ole days of aviation (which we simply cannot move on from it seems). Systems were very complex and highly mechanical in nature. All of them were controlled by human beings, hence the plethora of people in the cockpit of vintage airliners. The flight engineer literally made sure all the systems operated the way they were supposed to. The pilots flew and if present, the navigator made sure they didn’t get lost. The crew had to understand their piece of the equation and at least a little bit of the other guy’s in order to pull off the flight.

Fast forward to today where the airplane’s flight engineer is the ECAM that collects and displays information about the status of every system several times per second. You literally don’t need to know much more from an operational standpoint for many systems other than “Is it on?”, “Is it off?”, and “Should it be in that state?” A friend of mine flies a Brazilian-built regional jet and has to memorize the starting and operating temps, abnormal shutdown criteria, and various RPM ranges…for the APU. Meanwhile, the only direct control over this device the pilots have is an Off-On-Start switch, a Stop switch and an emergency fuel shut-off switch (in the event of a fire, overspeed or overtemp, the APU FADEC will automatically command a shutdown). Does it make sense that three switches with a total of five possible selections warrants memorizing the type of compressor, every temperature limit, every RPM limit, and the type of cooling used by the APU?

While it may be interesting information to know, the role of a modern airline pilot is not to play mechanic. It is to fly the aircraft from Point A to Point B. If there is a problem with the aircraft, they write up what isn’t working and if it isn’t on the MEL, continue flying until it can get fixed by the maintenance guys. It’s not about being cavalier, it’s about being efficient with specialized skills. Ask yourself if there is any way for a motivated captain to crawl back to the tailcone in flight (there isn’t since the APU is surrounded by a firewall). Even if they could get back there, what could they do to fix a problem? Last time I checked, airlines don’t hand pilots toolkits with their Jepp revisions. What if more time in review and sim sessions was spent talking about things that are more likely to be encountered in day-to-day operations, rather than the specifics of a component that the pilot will most likely never even see and has limited control over?

Air France 447 is a perfect example of why broad scale knowledge is critical. An aircrew faced with a rare and confusing situation may be spring-loaded to go to a rather complex solution due to the way we train them. Ignoring the control input issues, had the crew been taught to look at the big picture of where is the information coming from, they might have considered the fact that the FMGS was likely showing correct groundspeed based off the GPS signals it automatically updates with. Additionally, the combination of pitch and power for a given flight condition would have led to suspicion that the EFIS PFD was at least partially lying (and thus to look for independent data, such as the FGMS). This is not an indictment of the crew, but a look at how a few seconds to consider the big picture before zeroing in on a smaller picture solution may prevent accidents like this from happening again.

The Air France accident was not the first time a high performance jet was lost at night in the vicinity of thunderstorms due to faulty instruments. A nearly identical situation occurred in a B-58 on February 14th, 1963 when the pitot tube iced up and the pilot began unknowingly following erroneous airspeed data. When the controls felt sloppy and he suspected something was wrong, the pilot cross-referenced with the Machmeter, but this was also giving an incorrect reading. It wasn’t until the pilot asked the navigator (who had an independent pitot system) what the airspeed was that he realized the delta-winged bomber was about to drop out of the sky. The aircraft ended up departing controlled flight and the crew members were forced to eject (see the article “B-58 Hustler” by Jan Tegler in the December 1999 issue of Flight Journal for the entire story). Hopefully with changes in training and multiple-source independent airdata, there won’t be any more accidents like these.

Aerodynamics is another place where we overthink things to the point that it might be causing poor decisions in some situations. My favorite horse to flog is the recent bank angle conservatism being taught in the United States. There is no magic law of aerodynamics that says if you bank 31 degrees at 999 feet AGL, your airplane will autorotate into a flat spin. Although the intentions are good, the source of this fear stems from the g-load charts that we all looked at as student pilots. In a 60 degree bank, load factor is doubled and stall speed increases substantially. The only problem is that this is only true if you attempt to maintain altitude. It is not even close to accurate in a descending turn. Nor is it accurate if one is flying an airplane with a lot of excess power/thrust. We have become so obsessed with the book numbers that the bigger picture of how aircraft actually fly in three dimensions is being lost.

Don't freak out if you hit 60 degrees of bank while descending.

Don’t freak out if you hit 60 degrees of bank while descending.

There are student pilots (and an increasing number of certified pilots) who will either fly C-5A sized patterns, or make skidding turns in order to keep the bank angle low. The former negates the engine-out glide advantage of a close pattern while the latter actually is a perfect setup for a spin. To be honest, a bank beyond roughly 30 degrees is not really necessary at speeds under 80 knots if the proper lateral spacing is used. The trap is when the pilot comes in a lot faster or much closer due to ATC request or their own misjudgment. All of a sudden as they notice they’re going wide, the rudder gets kicked in and opposite aileron starts to hold the bank angle constant. The saving grace is that usually this situation is created by having a surplus of airspeed so a spin isn’t likely provided they return to coordinated flight fairly quickly. Rather than worrying about a chart that isn’t applicable to their conditions, they should be taught the confidence to put the airplane where it needs to be to get where they want to go.

Again, before people get riled up, there is a time and a place for sticking to book numbers. Early 727 pilots who tried to eyeball the landings as if it was a DC-3 with jet engines learned about the importance of sticking to the book. But the book isn’t magic. The numbers it contains are the sum of the properties of the atmosphere plus the aircraft’s design plus the systems installed. If it takes the engines 9 seconds to spool from flight idle to “Oh crap” thrust, the obvious solution is to not be low and slow while at idle. You don’t need to know how many stages are in the low pressure compressor (six total, two fan and four compressor) to get the big picture of why you keep the power up on final. Knowing the big picture of how heavily loaded swept wings behave at high angles of attack will also give you a better understanding of why simply lowering the nose won’t immediately get you out of trouble (plus the delay in thrust buildup to further compound your woes). It is true that sticking to the book will ensure that you arrive safely, but it is better to understand both the concept and the details.

Pilots cannot and should not know it all. The FAA regulation to “Familiarize yourself with all available information concerning that flight” is a rule designed so that if a pilot makes any error that “reckless and careless” doesn’t cover, the book can still be thrown at them. Rest assured that if you put one into the ground a half-mile short, you’re getting blamed for not getting a weather briefing despite it being CAVU with calm winds, flying an aircraft with an inoperative ADF and for not knowing the airport manager’s office phone number . This is a poor way to ensure safety but a great way to have instant blame in the event of an incident. Instead of scaring pilots into trying to read everything to fit some liability model, we should be encouraging them to select the appropriate data for what they want to do.

We collectively have to accept that despite what we would like to have everyone believe, 99.2% of pilots will never know every single little detail about their airplane. This should be instilled in student pilots via the way they are taught. Start with the basics and allow them to get used to the 3rd dimension. Instead of filling their heads with regulations from day one, ease off and let them enjoy flying. Let them have a few hours of wrapping their heads around controlling the airplane before revealing that they’re going to have to become a lawyer as well to understand all the regulations. Instructors can easily move from the big picture of “Let’s do our maneuvers up high so if you make a mistake we have plenty of room.” to the verbatim description of FAR 91.303 over the course of their training. The rules will make more sense anyway if a little bit of experience and common sense are applied rather than “you need to know this for the test”.

As usual, I’m sure not many people will read this (especially this far down) and those that do think I’m either full of myself, dangerous, a crusader or a combination of the three. The truth is I love aviation but I’m also willing to point to where we can do a better job making it less daunting for newcomers to get involved, safer for those already flying and more enjoyable for everyone. If we are honest, it’s time to admit that the act of flying is not very difficult in execution. Judgment on the other hand is what kills people. Being able to recite regulations does not stop people from flying into IMC or descending below minimums. Only the proper attitude and respect for the fact that you’re suspended in the air by the laws of physics and aerodynamics will make a person accept their own limits and those of their aircraft. This must be stressed more than any chart, schematic or diagram.

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Six Degrees For Separation: One Way To Solve The DFW Airspace Issue

The airspace over Addison (KADS) is slated to be changed soon if the FAA proceeds with its plan to reduce congestion into Dallas Love (KDAL) and Dallas/Fort Worth (KDFW). The airspace change includes a lowering of the Class D over Addison from 3000 MSL to 2500MSL. While that may not seem like much, it is in an area where operations are already in a very tight fit with DFW traffic to the west, DAL traffic inbound from the east-northeast and large amounts of corporate, fractional, cargo and training traffic underneath at ADS. In fact, the final approach fix (JERIT) for ADS rwy 15 is at 2000 MSL, which would leave only 500 feet separation between IFR arrivals into ADS and DAL traffic at 2500 if this airspace change goes through. As it stands, ADS is already the busiest GA airport in Texas and in the top 5 in the United States.

The area of concern: The 3000 MSL roof of Addison's class D is slated to be lowered to 2500 MSL, leaving very little space for aircraft as big as MD-80s and 737s to maneuver. The proximity to DFW and DAL is noteworthy.

The area of concern: The 3000 MSL roof of Addison’s already highly modified class D is slated to be lowered to 2500 MSL, leaving very little space for aircraft as big as MD-80s and 737s to operate. The proximity to DFW and DAL is noteworthy.

There are numerous ways to avoid having to redesign the existing airspace. Although I’m sure some will suggest vectoring airliners further to the north and west before their southbound turn towards DAL, this is not efficient with respect to the jets. Anything that increases fuel consumption for the airlines is not only irresponsible environmentally, but financially. Likewise, the hundreds of businesses that rely on ADS should not be marginalized in the effort to reduce the impact to airliners. I am not writing this from the standpoint of “big airliners are against little piston planes”. Instead, I am writing this as the result of several years of observing, studying and testing new methods of utilizing existing airspace. After reading the NPRM on the changes to DFW’s airspace, I came to the conclusion that people may not be fully grasping the true capabilities of modern jet airliners.

The upside-down wedding cake design of Class B airspace is optimized for steep climbs and descents. Standard Class B has a floor gradient of 300 ft/nm out to the 10nm ring. This equates to only 1000fpm at 200ktas or 1250fpm at 250ktas. But again, this is for the floor and operations in excess of these values would be well contained within the airspace. With the advent of RNAV STARs and GPS approaches, creating 3D highways in the sky is no longer a fantasy but an easily employable system that works in VFR or IFR conditions. The only way to fit more aircraft into the volume of airspace already set aside is to increase the angle of descent at critical segments inside the Class B.

For separation and flow purposes, many congested terminal areas drop arrivals down 30 or 40nm out so that departures can climb unobstructed above them. This is because in areas like the DFW Class B, the proximity of DFW, DAL, ADS, AFW, NFW, FTW, GKY, GPM and RBD makes it very hard to get everyone where they need to be at the same time. When most of the non-RNAV STARs were designed, it was hard to conceptualize how to position aircraft three-dimensionally. Now that airliners and many corporate aircraft feature VNAV, FPA symbology and the ability to climb or descend in excess of 2000fpm, being able to follow a constant descent path is much easier to plan and execute.

As mentioned before, the standard floor gradient for Class B is 300ft/nm. Modern jet aircraft can climb at more than twice this rate under most conditions. Descending is actually more difficult to manage in some cases as an angle which is too steep will preclude deceleration to flap and gear speeds. Testing this theory in various sims, talking to pilots of different aircraft and flying the procedure in real aircraft has shown that an average glide angle of 6 degrees results in a power-off approach with no increase in airspeed (in reality the range was roughly 4.5 to 7.0). Depending on configuration, very low levels of power may be required to maintain airspeed. This power setting will invariably be less than that used during the current step-down method of approaching. This has tremendous advantages for noise abatement, fuel conservation, airspace utilization and wake turbulence avoidance.

Jets are not as responsive as light GA airplanes in the approach phase which is why a 6 degree glide path converts to a standard 3 degree glide path at some pre-dplanned distance from the runway, most likely 1500 to 1000 AGL (depending on the aircraft type and wind conditions). Further out in the Class B airspace, descent angles can be more conventional if satellite airport conflicts are not present, allowing jets to “pre-configure”; going to a minimal flap setting that would produce enough drag to keep speed from increasing in the descent. Some aircraft that are extremely clean with high inertia such as the A330 and B777 may require shallower angles or the use of speedbrakes.

Using this type of approach in the northeast sector of the DFW Class B would bring Love arrivals over Addison between 3000 and 4500 MSL (depending on where they are vectored from). This is a substantial safety margin for both Addison and Love arrivals. An additional benefit is that Love’s lateral spacing would not have to be modified from what exists today, reducing the potential for conflict with Dallas/Fort Worth traffic on the Cedar Creek Six arrival when a south flow is in use. Around the DFW Class B, departures leave the terminal area on north, east, south and west headings, while arrivals enter on northeast, southeast, southwest and northwest headings. This existing deconfliction works well with 6 degree descent angle as departures would not risk losing separation with arrivals.

The whole idea behind the 6 degree approach is to use what we already have without making any particular group of operators have to suffer. If the procedure works well in our airspace, it can easily be implemented nationwide for reasons as varied as traffic management, noise abatement and reduced emissions. Please try this procedure in whatever simulators you have access to. An example to test out is DAL runway 13L, crossing WADES at 7500 MSL, NITER at 1900MSL and conducting a normal visual or ILS once crossing the FAF. Since this is an angle-based and not a rate-based procedure, your VS will change as you descend and or change airspeed.

KDAL ILS 13L 6 Degrees

Runway 13L Dallas Love. Note the modified IF crossing altitude to produce a 6 degree glideslope to the FAF.

If you want to convert any IAP to a 6 degree variant, simply decide what your conversion altitude or intersection is (when or where you go from 6 to 3 degrees) and how far back from that point you want to commence the approach. Applying basic trig will net you the IF crossing altitude. For example using DFW’s runway ILS 17L:

FAF = GBUSH, 2300MSL

IF = RIVET, Unknown MSL, 12.6nm from FAF

sin descent angle x distance to FAF x nautical mile in feet + FAF altitude

((sin6 x 12.6) x 6076)) + 2300 = 10302 MSL at RIVET

KDFW ILS 17L 6 degrees

Runway 17L Dallas/Fort Worth Intl. Notice the modified crossing altitude at the IF.

In the meantime, please send the FAA your comments and suggestions on the proposed airspace change. My solution is not the only one and the more minds that work on this issue, the better.

http://www.regulations.gov/#!docketBrowser;rpp=25;po=0;dct=PS;D=FAA-2012-1168

 

 

Aerobatics Undefined

At the airport the other day, we got into a discussion of FAR 91.307, lovingly known as the “parachute” or “aerobatics” reg depending on who you talk to. The point of confusion was that an instructor had been told by another pilot a while back that doing spins was illegal since they weren’t wearing parachutes. The concerned pilot had seen 91.307 (c) and assumed that since spins exceed 30 degrees of pitch in most cases, that the reg had been busted. However, reading further to 91.307 (d) (2) it clearly states that spins and other checkride-required maneuvers are legal to fly without a parachute. In fact, there is no restriction on attitudes whatsoever provided everyone in the aircraft is a crew member. Actually, 91.307 (c) gives us a lot more latitude than we think. It states the following:

(C) Unless each occupant of the aircraft is wearing an approved parachute, no pilot of a civil aircraft carrying any person (other than a crewmember) may execute any intentional maneuver that exceeds–
(1) A bank of 60 degrees relative to the horizon; or
(2) A nose-up or nose-down attitude of 30 degrees relative to the horizon

If you and a fellow pilot go up and do a 90 degree bank wingover, you do not need parachutes. If you go up solo and pitch up to 50 degrees and do a reduced-G float over the top, that’s legal without a chute as well. If you take your non-rated friend up, you either have to provide parachutes for the both of you, or keep the angles to the 30/60 limit. Also, if you and 3 other pilots go up, the 2 pilots in the back seats do not count as crewmembers so the 30/60 limitation will also apply. Note, that 30/60 is not the boundary of aerobatic flight. The litmus test for what defines aerobatics for your aircraft is in the operating manual. If your manual states that aerobatics are not approved except spins, Chandelles, accelerated stalls and Lazy-8s, then you know that rolls are out of the question. But nowhere in the FARs does it describe aerobatic as being flight in excess of 30/60 degrees. FAR 91.305 defines aerobatic flight as:

For the purposes of this section, aerobatic flight means an intentional maneuver involving an abrupt change in an aircraft’s attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.

That’s pretty vague, probably one of the most open ended regs next to 91.119. What defines abnormal? What is abrupt? And what is normal flight? I get the feeling when this was written, it was with point to point transportation in mind. As such, the regulation is conspicuously open-ended to allow for other types of operations that involve more aggressive maneuvering. The catch is that the FAA can also randomly define what “normal” and “necessary” is in response to a complaint or to issue a violation. But there is still another catch. “Aerobatic” also counts as a category of aircraft.

Say that I’m out over farm fields at 3,000 feet AGL in a utility category airplane doing wingovers. My airspeed never even gets into the yellow arc and my G-load never goes over 2.0. An overeager observer down below assumed that I was “hot-dogging” and “barnstorming” and called the FAA to say that I was doing “flips and tailspins in a Piper Cub” (it’s always a Piper Cub to non pilots). Short of having a data recorder onboard, its my word against theirs. Lacking this hard data, its very hard to validate what you did or did not do. And knowing what maneuvers were flown is critical in order to defend yourself. After all, it is entirely possible to do “aerobatics” in normal category airplanes without imposing more than 2Gs on the airframe. Before you get angry and call me dangerous, I’ll explain.

While it would be tempting fate to do a snap roll in a normal category aircraft, you can freely apply full control deflections (well below Va and in one direction only), pitch, roll or yaw to whatever attitude you like. The danger is in building up too much speed in an extreme nose low attitude and needing to pull more G than the airframe is rated to (that’s when you hear the loud POP and then enjoy the rush of the wind as your wingless, tailless airframe plummets to earth). However, an abrupt change in attitude does not always imply a high load factor. Imagine using full aileron in a Piper Saratoga to roll into a steep turn (50 degrees) quickly. Was the maneuver abrupt? Compared to “normal flight” in the same type airplane, yes. Is the attitude abnormal? Not really? Was the acceleration abnormal? Not even close. So was it aerobatic? Ask your FSDO…seriously, find out how they define it.

The more knowledge you have about what you’re doing, the better. An untrained observer may say that they saw an airplane doing “acrobatics” and “stunts” when really you were doing Chandelles. If you can confidently state what maneuvers were performed along with some rudimentary info on entry altitudes and speeds, it may convince whoever is inquiring that you aren’t just throwing the stick around to see what happens. Unfortunately, society loves to point out when they think someone else is doing something wrong or unsafe without actually knowing what was going on in the first place. If you take the chance of actually having fun in other than straight and level flight, there’s the risk that someone with an iPhone is going post video of everything you did while commenting on how “unprofessional” and “dangerous” the pilot of that little airplane was.

Quite frankly, every time you fly, you are at the mercy of someone’s self-narrated cellphone video (even an airplane well above 1,500 feet AGL will show up on a phone camera). The only way to protect yourself legally is to make sure you understand the regulations fully. However, the only way to keep yourself alive is to make sure understand the aerodynamics fully. Use 91.307 to your advantage. Go up with an instructor and practice really unusual attitudes. Take some aerobatic lessons. Get used to the fact that airplanes operate in a three dimensional ocean of air. If your comfort zone ends at 30 degrees of bank, work your way up to 45 and 60 degrees (maybe even a little beyond). Once you experience that an airplane will not just drop out of the sky because the bank angle increased beyond 45 degrees, you will have a lot more confidence in handling it in all phases of flight.