Top Letters And Comments, February 7, 2020


Common Sense vs. E-Everything

My impression is that nearly all discussions of electric propulsion omit the fundamental problems of physics that limit the whole enterprise: the energy density of batteries.

Of the three obstacles standing in the way of electric propulsion (energy storage, efficient electric motors, motor controllers) two have been solved. Small, lightweight, three-phase electric motors now operate in the high-90% efficiency range. Light, powerful motor controllers which not only provide throttling but generate from DC sources like batteries the three-phase AC power the motors need? Done.

What will be very hard to overcome is the basic physics that currently gives internal combustion engines a tremendous advantage. Firstly, gasoline is extremely energy-dense. (Which has more energy, a pound of gasoline or a pound of TNT? Gasoline – by a factor of about 15:1). Secondly, of the reactants that generate energy, the airplane only has to carry about 1/15th – by WEIGHT. At a mixture of about 15:1, for every pound of gasoline burned, fifteen pounds of oxygen are pulled out of ambient air, and then the exhausted gasses (sixteen pounds of them) are simply dumped back into the atmosphere. And as we all know, weight is the nemesis of the airplane.

Batteries, on the other hand, must carry everything necessary to store every kW-hour of energy required for a given flight. Lithium and other lightweight materials aside, it is going to be very difficult to overcome that deficit. Probably the best hope is some form of the hydrogen fuel cell, which – like internal combustion engines – also uses atmospheric oxygen. Failing this or some other major breakthrough, though, don’t hold your breath; electric propulsion on a scale equal to burning hydrocarbons ain’t coming any time soon.

James W.

One of the first things that came to mind when I read about battery-powered aircraft is that they don’t lose weight during the flight. I’ve read that an airliner flying from Toronto to the U.K. uses half of its fuel to reach its cruising altitude and the rest to cross the Atlantic. A battery weighs the same whether it’s fully charged or “empty”. That means its landing weight is the same as its takeoff weight, which in turns means it will need a stronger airframe and landing gear to withstand the higher impact forces (unless every pilot of an e-plane can achieve a 100% rate of greasing it in).

This does not mean that e-planes cannot be made, or be practical, but it’s something that’s rarely mentioned in any discussion of their pros, cons, and potential. I think it should be.

Jeff R.

Baby steps.

We didn’t go from the Wright brother’s first flight to the 787 in a few years. We didn’t go from the Motorolla brick to the iPhone 11 overnight. To quote one of my favorite TV shows from the past, “Patience Grasshopper.” The industry is in the very earliest stages of electric aircraft development, give it time. Research the battery technologies that are in the lab now, as the NiCad and lithium-ion were at one time, you will see the technology is coming.

Kevin R.

Poll: Should TAWS Be Required For Helicopters?

  • A standard for TAWS needs to be developed first. There are a variety of avionics, tablets, and pilot apps that provide TAWS. After deciding what the minimum parameters are for TAWS then we can decide where it is mandated.
  • Helicopters operate in the low altitude environment and most HTAWS systems provide many false alerts, negating their usefulness.
  • Electronics, in any form will never make up for poor PIC decision making.
  • For the preponderance of helicopter flights, TAWS is a waste of payload and money. If required to prevent CFIT for helicopters, then TAWS MUST be considered as critically necessary for every GA airplane too!
  • HTAWS is only effective if you fly above the terrain. Helicopters often fly below ridge lines among the terrain and with the current granularity of databases, these tend to activate warnings all the time. The brain becomes accustomed to on-sense warnings and you don’t heed the one that is real.
  • Based on what we know (which may change), TAWS would not have prevented the Bryant crash. I dislike knee-jerk “fixes,” especially when it’s unclear if they even address the problem they are meant to fix.
  • HTAWS is great for IFR or obstacles VFR. For VFR in the mountains it is an annoyance.
  • For commercial operations, maybe. Bolting in an EFIS from the homebuilt market would provide it at a fraction of the cost of the eventual certified system that will be mandated. Can’t have that, though…
  • At the very least, have GPS Terrain Display!
  • No, they fly low and it would be constantly going off.
  • Depends upon how they are being used.
  • I think the NTSB’s recommendation to require all existing and new U.S.-registered turbine-powered rotorcraft certificated for six or more passengers to be equipped with TAWs is reasonable.
  • For hire aircraft, yes. However, consideration need to be made which would impact performance abilities.
  • No, except for certain specialized operations.
  • I’d like to see GPS/AHRS derived synthetic vision required.
  • EMS helicopters only. Many already have it.
  • No amount of terrain awareness can substitute for solid pilot judgment. I have TAWS in my Mooney and also on my iPad, but unless I maintain a safe terrain clearance, I too will fly into the terrain. In this case, it appears the pilot climbed into the clouds, became disoriented and crashed at high speed. TAWS is merely one more tool in a pilot’s bag.
  • Commercial yes, but 133/137 exempt.
  • HTWAS is a BIG cockpit distraction most often turned OFF.
  • For IFR ops.
  • Don’t fly in clouds if you’re not on an IFR flight plan.
  • Synthetic Vision serves the same purpose as TAWs and won’t cost nearly as much.
  • ForeFlight works! No excuse for running into anything! 8,000 hours doesn’t make you a better pilot than 500 hrs. Must have enough sense to know when to park it. That pilot killed 8 people needlessly.
  • Helicopters with more than 9 passengers. However, it would not have prevented this bad judgement.
  • If IFR certified.
  • TAWS or not can’t solve the inherent instability of a helicopter in IFR.
  • Fire flight TAWS is fine – don’t need more.
  • I know that TAWS works.
  • Synthetic vision would be much more effective.
  • Commercial helos above some passenger threshold seems reasonable.
  • It will not work in low-level helicopters.
  • Technologies like EVS combined with Syn Vis offer a more preventative solution.
  • For large helicopters, yes.
  • No, if operation is restricted to VFR only.
  • Even more so than fixed wing.
  • Do we really think this pilot was unaware of the terrain?
  • It may make more sense to set higher SVFR minimums for part 135 helo operators w/o TAWs, then leave it up to the operators whether to adopt or not.
  • VFR helicopters should stay VFR and IFR helicopters should have HTAWS.
  • Another knee-jerk reaction to a celebrity death.
  • Sure, just stick it in the Ops Specs, and be done with it. Let FAA Air Carrier or GA Division make the call.
  • No. The constant alerts will eventually tuned out by the pilot.
  • For commercial aircraft (fixed wing or helo) absolutely. Money should not be factor
  • Commercial IFR operations.
  • TWAS is another tool. It can cry wolf to the extent that pilots simply ignore its constant nagging.
  • Is there time enough when flying so close to the ground at high speeds for the information to be useful? I doubt it.
  • Not required but if not equipped they should be restricted to daylight VFR only.
  • Every aircraft should have it, it’s cheap tech until the FAA gets involved.
  • Required is too strong a word. Highly recommended for IFR certified “Commercial” helicopters.
  • Of course not, it’s not required in other aircraft.
  • We don’t need more government intervention.
  • For SVFR and IFR ops for hire.
  • Any helicopter with 6 or more seats.
  • For all aircraft.
  • Part 135 and 121.
  • It would be great in some circumstances. But would it promote continued reliance on automation?
  • Synthesized environmental displays will be required on all future flight vehicles.
  • Depends on the mission.
  • Everyone should have it.

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  1. Vertical take off with batteries has even a bigger problem. Here is a good way to illustrate the load on batteries: If your car dies on the road – most people can push it off the road on a level hard surface. Now picture in your mind how many people would be required if you want to get under the car and push it straight up! That is the difference between an airplane and helicopter. From day one, we have always said that the only way to do it is to use an onboard generating system. So far, the use of fuel cells is still too low in amps, even if hydrogen is produced onboard.