Tuesday, May 31, 2011

Can LightSquared 4G and GPS Coexist?

There's a common line of thinking among some folks in the aviation community that the federal government doesn't restrict cellphone use in an airborne aircraft, that cellular telephones do not interfere with radio navigation, and that it's fine to use a cellphone or have it powered on in flight. The usual reasoning I hear from pilots who leave their cellphones on or use them in flight is that since they've never seen any problems, no such problems exist. The fact is that we are surrounded by an ever-growing sea of radio frequencies and detecting interference requires a more rigorous approach than casual observations made by individuals. If you need more convincing that radio frequency (RF) interference can be serious, look no further than the proposed LightSquared 4G broadband network and the impact it may have on GPS users.

Never Seen a Leprechaun

It's understandable how some pilot's come to the conclusion that cellphone use is okay in an airborne aircraft since the relevant aviation regulation, 14 CFR 91.21, appears to permit cellphone use if the operator or pilot-in-command has determined there's no interference or if the flight is conducted under visual flight rules. The regulation provides no guidance on how one is to test for interference and that could lead one to conclude that the FAA doesn't care if you use your cellphone in flight. Consult the portion of the Code of Federal Regulations that deals with the FCC to find the regulation, 47 CFR 22.925, that clearly and specifically forbids the use of cellular telephones in flight. The FAA may not care, but the FCC clearly does care.

The common follow-up argument is that the FCC ban is out-of-date and that there's absolutely no problem with leaving your cellphone on or using it in flight. Folks who make this assertion usually do so based on their personal experience in their own aircraft. An important element in this line of thinking is a strong desire to do what is convenient, not so much on any rigorous measurements of radio frequency (RF) interference. While I haven't made any specific measurements with sophisticated equipment, I have noticed several basic types of cellphone interference in aircraft.

In one aircraft I occasionally fly, one of the two VOR receivers will show a 15 degree error at a ground VOR checkpoint whenever an iPhone 4 is turned on and placed in the console directly below the radio stack. Put the iPhone 4 in airplane mode and the VOR error goes away.

I've also demonstrated interference between cellphones and my portable Zaon PCAS MRX traffic detector that manifests as false traffic alerts. It took me a while to correlate this, but on several occasions the Zaon MRX gave continuous traffic alerts for an aircraft within a mile and at the same altitude. Asking ATC if they saw any traffic in my area always resulted in the same response: "Negative." On one such occasion, we heard the unmistakable sound of cellphone data transmissions over the intercom (dit-da-dit-dit-dit-dit-dit ...). When we located the offending cellphone and put it into airplane mode, the intercom interference went away and so did the phantom aircraft that the Zaon MRX had said was within 0.3 miles and at the same altitude.

Just because you've never seen a leprechaun, that doesn't mean they don't exist.

4G vs GPS

While I've never been able to correlate cellphone interference with GPS receivers, at least one next generation 4G network system appears to pose a widespread threat to GPS accuracy. The FAA has been issuing NOTAMs over the past several months warning of potential GPS unreliability related to the testing of new 4G network equipment created by LightSquared.

In January of this year, the FCC issued a waiver to LightSquared allowing them to move forward with plans to deploy transmitters that uses the L band 1 spectrum to provide a high-power terrestrial broadband service. While this could be great news for people in remote areas that want high-speed data transfer on their mobile device, GPS experts and users are concerned. The 1525 MHz-1559 Mhz band is very close to the 1575.42 Mhz band used by GPS.

Recent tests of LightSquared's 4G equipment has inconvenienced many users of GPS. On one occasion, I was unable to get a clearance to fly an RNAV approach because the NOTAM prevented ATC from allowing such approaches during the testing. Imagine aerial survey companies who rely on WAAS GPS to do their mapping or ships that rely on GPS for maritime navigation. Aside from acquiring the necessary equipment and databases, GPS is provided without charge. The LightSquared 4G product will undoubtedly be a commercial product and user's will understandably have to pay for data access. Whether it's the profit motive or a large number of lobbyists, the implementation of LightSquared's network is continuing at a rapid rate.

Hope you like Jammin' Too

Testing done by Garmin showed that an automotive nuvi 265W GPS receiver was jammed when within a 3 to 4 mile distance of a LightSquared transmitter. Garmin's aviation GPS receiver tests were even more sobering with jamming of a 430W occurring within 9 to 13 miles of a LightSquared transmitter and a total loss of position occurring within 5.6 miles.

The waiver granted to LightSquared by the FCC requires that a working group identify and reconcile conflicts between 4G and GPS, but the onus appears to be on the GPS community, not LightSquared:

Because the GPS interference concerns stem from LightSquared’s transmissions in its authorized spectrum rather than transmissions in the GPS band, the Commission expects full participation by the GPS industry in the working group and expects the GPS industry to work expeditiously and in good faith with LightSquared to ameliorate the interference concerns.


The FAA has gone to considerable lengths over the past several years to create RNAV approaches with vertical guidance and to expand the WAAS service volume. With the number of LPV approaches outnumbering the number of ILS approaches, the potential conflict between GPS users and companies that want to provide satellite-based broadband is very, very serious. For my money, it's more important to have accurate RNAV than to be able to update my Facebook page while hiking the John Muir Trail.

LightSquared reportedly wants to install up to 40,000 high-power transmitters operating at up to 15,000 watts (42 dB). So the latest threat to the integrity of GPS isn't solar flares or aging satellites, it's wireless broadband. Until this gets resolved, be sure to check those NOTAMs. And if you haven't practiced navigating with VORs lately, you might want to dust off those skills.

Wednesday, May 18, 2011

Going Around

Based on persistent news reports, it's clear that someone needs to help the non-piloting public understand a few things about landings, go arounds, and missed approaches. Several media reports have been describing aircraft go-arounds or missed approaches in a way that implies someone made a mistake or danger may have been involved. So in the spirit of The Onion, I've taken up the gauntlet. Here's how expanded media coverage on go-arounds or missed approaches might eventually read.


Aborted Landings Linked to Flight Instruction 

(Berserkly News Network) Oakland, California -- While veteran flight instructor John Ewing was supervising his student pilot's landing practicing today, he instructed him to "go around." In that moment, Ewing had no idea of the controversy that was to follow.  In the wake of recent high-profile aborted landings, first of the plane carrying First Lady Michelle Obama on April 19 and then Air Force One today, FAA administrator Randy Babbitt announced that he has instructed all FAA personnel to record and report each and every go-around that occurs. Babbitt, under increased pressure, wants to reassure the public that pilots really do know how to land their aircraft.

"When an aircraft has been cleared to land, we expect them to land, dammit!" Mr. Babbitt said. "The US government didn't authorize the creation of all those runways just so pilots could fly around in circles without landing."

As soon as the order came down, tower controllers around the country began to complain. "This is like being asked to count all the fish in the sea," complained one Oakland Metropolitan Airport controller, who asked not to be identified. "How are we supposed to ensure the orderly flow of air traffic when we're filling out paperwork each time an aircraft goes around?"

Right after Ewing's student informed the Oakland Tower of their intentions to abandon the landing, all hell broke loose. "The tower told us to make right traffic and that we were cleared to land on 27 right, no ifs, ands or buts" Ewing stated. "We reminded them that we were practicing touch-and-goes, but they just repeated the clearance to land," Ewing said. "After my student landed, the ground controller said they had a phone number for us to call." What followed was the nightmare every pilot dreads.

"They interviewed me, they inspected the aircraft and my certificates, they asked why we went around, and I tried to tell them that my student's approach was destabilized. I was just teaching him to do the safe thing," Ewing said "but they said all these go-arounds indicated instructors like me were doing a piss-poor job." In the end, Ewing was exonerated and allowed to continue to teach the go-around maneuver. "The go-around is in the private pilot practical test standards," Ewing observed. "I mean, for crying out loud."

But the controversy surrounding go-arounds hasn't ended. Babbitt, under intense scrutiny, announced NextGen will be modified to automatically record data on each and every go-around or missed approach. In addition, each and every landing made by any pilot will be rated on a scale of 1 to 10. Pilots executing an excessive number of go arounds as well as those who don't consistently perform flawless landings will be automatically notified that they must undergo remedial training. Cost estimates for adding these features to NextGen were unavailable. NextGen implementation has been delayed, but is slated for roll-out sometime in 2095.

All of this hasn't deterred Ewing from continuing to teach student pilots how to fly. "Sure, I could throw in the towel and go work for Starbucks," Ewing said, "but then I'd have health care benefits. Besides, I'd just be watching espresso magically come out of a machine without any grinding or tamping of coffee whatsoever. Where's the fun in that?"

Monday, May 16, 2011

Rumors of my demise ...

The last few weeks have been hectic and have offered precious little time for writing blog posts. A trip to SoCal, some pressing house projects, and a busy teaching schedule all conspired to keep me otherwise occupied. Nevertheless, I've been reading, flying and teaching and have been making mental notes about blog-worthy topics.

CFI Punching Bag

Two of the current hot topics in GA are the shrinking number of pilots and the effectiveness of flight training. The newly revised Flight Instructors Model Code of Conduct is the latest installment in the "what's wrong with flight training" discussion. AOPA started banging this drum at one of their conventions and has been repeatedly mentioning it in virtually all of its publications and emails.

Like it or not, we live in an age where public discourse and debate often involve a peculiar use of language and a reliance on repetition to manufacture consent. Whether you call it double-speak, framis, or baffle-gab, we are bombarded with repetitive slogans designed to appeal to emotion rather than intellect. Using logic and reasoning requires us to get our thoughts in order, assemble the facts that are known, consider competing claims, and simultaneously hold conflicting ideas in our minds so that we may evaluate them: In short, it's hard work. The fact that someone saw the need to create a model code of conduct for flight instructors (there's one for mechanics and others, too) would indicate that there are problems within the flight instruction community. Just what those problems are depends on one's perspective.

The code addresses instructor responsibilities, training and proficiency, security, environmental issues, using technology, and promoting aviation instruction. Just a few of the stated benefits of adopting this model include improved pilot training, personal responsibility, instructor contributions to society at large, self-regulation as an alternative to regulations, and promoting recognition of instruction as a highly respected and rewarding profession. The code encourages instructors to be respectful of the risks and dangers of flying, act like professionals, manage stress and fatigue, conduct their flights like airline pilots, and not have sex with their students. The opposite of this sounds like pretty average behavior for 17 to 22 year olds and though I don't have the data to back this up, this is likely the average age range for the majority of active aviation instructors.

What the Market will Bear

The most important aspects of aviation safety start with flight instruction, yet CFIs are enduring low pay and long hours. Regulations allow CFIs to give up to 8 hours of flight instruction per 24 hour period, 7 days a week, 365 days a year and that's what many instructors do just to make ends meet. By the time an instructor has finished teaching his or her second flight lesson of the day, the instructor's ability to provide quality instruction has likely been exhausted. Income levels that encourage instructors to teach three or more lesson per day do not contribute to high-quality learning experiences or professional behavior. The mere existence of a model code of conduct is not going to change the situation.

Most pilots become instructors because they dream of a better flying job and to get that dream job, a young pilot needs to log flight time. So many instructors are a young, motivated group at the bottom of the aviation food chain desperate to provide low-cost labor in exchange for flight time. This is an aviation tradition that the FAA has long supported if not enabled outright.

There's absolutely nothing wrong with pilots who do a stint as an instructor so that they can move on, but let's not cloak it in high flautin' talk about professionalism, high levels of proficiency and customer service. This is a business relationship between employers and employees, plain and simple. The profit margins in aviation are so razor thin there is no way to pay instructors like professionals. The mere existence of a model code of conduct is not going to change the situation. One benefit of the current flight training model is that it separates the wheat from the chaff because by the time an instructor is ready to move on to an airline job, they will have already been acclimated to long hours and low pay.

Easy Target

Flight instructors are the most active pilots in the GA community, they fly more hours than the average GA pilot, and they are crucial to training the next generation of pilots. The impact of flight instruction on the pilot population is unmistakable, but there are many reasons why student pilots decide to drop out. AOPA says that the cost of flight training, aircraft rental, and aviation fuel are not important factors. I find this claim to be utterly fantastic and unsupported: The folks they are sampling in their research must travel in different circles than the pilots I talk to.

While AOPA and others are busy trying to "fix" the flight training model so that fewer pilots drop out, little is being done to improve the average flight instructor's day-to-day life. Quite the opposite, from where I sit the solutions being put forth simply perpetuate the status quo with regard to flight instructors' working conditions.

Flight instruction, like all aviation endeavors, is a tough business. Learning to fly is a difficult, complicated, and expensive proposition. Those who stick with it, whether we're instructors or weekend flyers, do so because we love aviation. I'm all for making the flight training experience as rewarding and efficient as possible. I strive to do my best as an instructor because I enjoy teaching, mentoring other instructors, and helping pilots reach their flying goals. Being a CFI is one of the most rewarding things I've ever done, in spite of the hardships that come with living at the bottom of the food chain. From my perspective the model code of conduct is, at its best, a distraction and, at its worst, insulting. The efforts of AOPA and the folks who authored the Flight Instructor's Model Code of conduct may be based on good intentions, but good intentions can also lead to a decidedly undesirable destination.