Products, Regulatory

What’s the Deal With the Radio Altimeter Requirement for Robinsons?

By Tim Kern | April 6, 2018
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Robinson Helicopter R44 Raven II. Photo by Tupungato

Once in a while a camel emerges from the lab, the result of committees' tweaking DNA to build the perfect horse. Federal Aviation Regulations 135.160 may be an example.

Today, all Part 135 operators of Robinson R44s and R66s are uniquely (in the under 2,950-pound gross-weight class) required to install radar altimeters (RADALT). There is no mandate they be turned on, there is no mandate for additional pilot training, and many operators say they are useless or worse in their missions. What happened? What is being done?


The original 2014 NPRM's reasonable purpose was “to address an increase in fatal helicopter air ambulance accidents."

The military has used RADALT for decades, and many helicopter emergency medical service (EMS) units wouldn’t be without it. However, realizing that so many of the smaller ships, unsuitable for most EMS activity due to load capacity and cabin configuration, are better matched to missions that are overwhelmingly day VFR. The industry was not alarmed, expecting a common-sense LODA for those operators who are not likely to fly night missions, or into whiteout, brownout or IIMC.

The FAA cited an NTSB safety recommendation that urged the FAA to "require the installation of radar altimeters in all helicopters conducting commercial, passenger-carrying operations in areas where flat light or whiteout conditions routinely occur."

But the FAA ignored the second part of the recommendation, and wrote in FAR 135.160:

(a) After April 24, 2017, no person may operate a rotorcraft unless that rotorcraft is equipped with an operable FAA-approved radio altimeter, or an FAA-approved device that incorporates a radio altimeter, unless otherwise authorized in the certificate holder's approved minimum equipment list.

(b) Deviation authority. The administrator may authorize deviations from paragraph (a) of this section for rotorcraft that are unable to incorporate a radio altimeter … applicable to rotorcraft with a maximum gross takeoff weight no greater than 2,950 pounds.

Some in the industry responded immediately, like Helicopter Association International VP of Operations Paul Schaaf, who said such requirements are costly.

But most of the industry took little notice, counting on a letter of deviation authority (LODA) — until they applied and were denied.

The R44 had a factory kit available and therefore wasn't "unable" to comply. So part 135 operators of R44s must now install and maintain a single-sourced RADALT system, though its use is not required under any circumstances.

During the comment period, the FAA dismissed arguments that HTAWS may be a better idea, since RADALT units "tell distance to where the aircraft has already been, not where it’s going to impact," and that "radio altimeters are unreliable [and] give erroneous information over snow-covered surfaces." And sea swells, trees and waving grass.

The FAA quoted the NTSB: "A radio altimeter could have provided the pilot with a low altitude warning, enabling the pilot to take corrective action," ignoring that several other systems (HTAWS or even synthetic vision) could also do that.

In fact, all 196 comments were dismissed, many without any discussion at all.

Would RADALT help?

The FAA cited 29 accidents covering all models of helicopters, 19 of which "might" have been prevented by RADALT. However, specifically addressing U.S. fatal accidents in R44 models between 2000 and 2013 inclusive, the NTSB database revealed two accidents. The 2007 accident (four fatal) was in day VFR conditions, immediately after takeoff and was attributed to weight, a tailwind and high-density altitude.

The 2003 accident took the life of the 15,000-hour pilot (7,500 in rotorcraft) in a 730TT, GPS and skid float-equipped machine, over water in the dark. Though one might speculate that the pilot could have used RADALT as he brought parts to an offshore rig, the facts remain under salt water.

Some of the confusion over the NPRM could be due to phrasing like that in OpSpec A-160: "Deviation authority may not be warranted for helicopters in which an RA can be added to the flight deck’s existing configuration." Did that say, since there is no room on the existing flight deck of an R44, a LODA would be granted?

The FAA said, "HTAWS or other devices, such as a multi-function display that incorporates an RA, would be permitted under this rule," but the paragraph continues, "the certificate holder may not use information derived from a global positioning system (GPS) as a substitute for an RA."

One prospective R66 operator wrote to me, "To add to the confusion, the FAA is saying that an R66 would never have to comply with the RA requirement because at the time this FAR was adopted, no STC solution existed for the R66."

Planning and good intentions are not sufficient. Part 135 operator Dale Schneider's new Bell 505 was scheduled for April 2018 delivery and he figured, “I’ll order it with a radar altimeter and forget about it, and tell the FSDO I need a LODA for my R66 until then. Denied! 'OK, I just won’t operate under 135 until then.' Also, 'No, because you can’t keep a 135 certificate without having a 135-eligible aircraft.'"

Dave Hynes owns all three Robinson models, but only the R44 is on his certificate. "I transport passengers 50 to 60 miles from Virginia Beach. Personal transport — 95% is daytime VFR. We read [the NPRM], and 2,950 caught our eye. We figured we'd put in a request for a deviation. … Then others put in a request and were denied. What do we do now, and how in the world is RADALT going to do a thing for our operations?" He did eventually receive a temporary LODA.

Maria Langer, managing member and chief pilot at Flying M Air, uses her Raven II to take tourists to wineries or other points of interest and "some 'executive transportation,' normally within one hour of my base." Additionally, she said, "I fly photo missions, wildlife surveys, rides at outdoor events and custom tours," almost all of it during daylight hours. Like so many of those now affected, she did not comment "because I never imagined it could apply to me and my VFR-only operations."

Her one experience with RADALT (a ferry flight) wasn't positive. "I found it a nuisance because it was constantly warning me about altitude and obstacles, even though I averaged about 700 feet agl."

Even Robinson Helicopters was blindsided.

"This NPRM came from a different direction: EMS. We were caught a little flat-footed because we just didn't see the universal nature of the NPRM. We developed the kit as a courtesy to our customers, the handful of operators who had a demand for RADALT; usually they're operating over water, on boats, that sort of thing,” said Kurt Robinson, president and chairman of Robinson Helicopter.

Robinson has seen pushback from VFR-only operators as well.

"They really don't need it,” said Robinson, adding that the OEM costs are “about $16,000 to $17,000,” and STCs are available for an estimated $13,000.

"As far as we know, there's no exemption," Robinson said. "We were under the impression that it was for the HEMS operators, so Robinson didn't comment, as we offer a kit as an option, and there's field-installable kits available, too. We didn't have a kit initially for the R66, so some early customers got waivers, but we are developing one now."

For the final regulatory evaluation, the FAA determined cost to be $9,000 for the device, which was the highest estimate given by commenters, plus $500 annually for maintenance. Though there is no requirement to use the system. The RADALT option on a new R44 lists for $16,700.

Schneider researched the part numbers listed in Robinson publication KI-228; the actual RA 4000 can be purchased separately. Dale shopped shows and discounts, saving about $3,600.

Langer had to fight tooth and nail — with the assistance of a lawyer, congressman and senator — to get a temporary LODA. It took a little over a month.

“While I was waiting, I was forced to pass up five Part 135 charter flights," said Langer. Her temporary deviation lasted only through 2017. She is now paying for a system that represents "a financial burden for an unnecessary instrument that would likely distract me more often than enhance safety."

Interestingly enough, one of the required parts is a $11.75 decal that says, "Caution: indicated ALT lags actual ALT during descent."

Very few failures of RADALT systems are recorded, though the Dutch investigation of Turkish Air’s fatal 737 accident in 2009 opines that non-repeatable failures are often unreported. (Here, one of two RADALT systems failed and remained coupled to the autopilot on approach — not a "helicopter" type accident.)

The FAA provided an emailed response to an inquiry about the radio altimeter rule. Addressing the safety impact of equipping with radio altimeters, the agency cited an NTSB safety recommendation that notes “radio altimeters might aid pilots in recognizing proximity to the ground in flat-light and whiteout conditions.”

"Additionally, the FAA cites 29 accidents in the final regulatory evaluation that may have been prevented by a radio altimeter. Of the 29 accidents, 19 were classified as controlled flight into terrain by the NTSB. A radio altimeter could have provided the pilot with a low altitude warning, enabling the pilot to take corrective action,” the agency said.

Regarding the available exemption from the rule, the agency notes that rotorcraft weighing “less than 2,950 lbs” and those “unable to to incorporate a radio altimeter due to physical or electromagnetic limitations or if there simply isn't a viable solution on the market” are allowed a deviation from the rule. There is also a conditional allowance of “OpSpec A160 for rotorcraft (e.g. R44s) that had a radio altimeter solution available during the three-year compliance period in order to allow those rotorcraft the benefit of a full three-year compliance time,” the agency said.

"The bottom line is that R44s need to comply with the radio altimeter equipment rule,” the FAA said.

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