Thoughts On Cockpit Electronics

Recently I was playing an EFB type app. I think I've mentioned it on my other blog, and I am mostly happy with Avare. This app will allow weather downloads, and is a moving map and can display charts of most types (Sectional, WAC, IFR Low and High, etc). It has built in AF/D, can display approach plates, and topographical data.

While using it, I was surprised by a few things, and it occured to me you cannot just buy the latest technology and go out and blindly rely on it. You really need to know how it works, and test it out for a while.

I flew with the Avare app on a Samsung Note 10.1, and found a few anomalies with the system, and I am sure other apps and tablets have similar anomalies. I was testing the app out while riding in the back of a 737, and the GPS was mostly unusable back there. On takeoff it seemed to work well and I could see the acceleration down the runway, and the climbout was displaying nice. But about the first turn, and suddenly the GPS wasn't working at all. No speed, no heading, nothing. Then it was intermittent the rest of the flight.

Avare, like most moving map applications can take another GPS source as the input. There are several manufacturers that offer standalone GPS source devices (IE Garmin). Avare even offers an app you can run on another device (IE phone) to use that GPS source to feed the application. On my next flight, I ran the external app on my phone, and was feeding Avare with the GPS output from my phone. The phone was in my pocket, and I had a window seat, so it worked almost 100% of the flight.

Since the my phone GPS wasn't 100% reliable, it was a good test. I've mentioned Kalman filters in other posts, I wanted to see if this app had any coast mode, where the application would predict the location based on flight plan and last few samples, but it didn't. When the GPS signal was lost, the airplane on the magenta line would point straight north, and stop updating. This by itself was a good thing to know, since GPS isn't 100% reliable in any situation (see the RAIM predication post), and it is good to know what indication is out there when the GPS signal isn't there. When the GPS data was available again, the airplane symbol oriented itself to the flight path the aircraft was following.

Another test I found out about, the hard way, was the chart updating. The charts are generally current for a period of time, some are 28-56 days (IE approach plates) and others up to about 6 months  (IE sectionals). Some of my charts were out of date. The app has a nice feature allowing bulk downloads of charts, but not while out of WiFi range. Most charts are big files, that take a while to download. Even a 737 with WiFi on board isn't the best place to bulk download charts, since most of the flight may have taken place by the time it updates everything (depending on how many plates are out of date). It is best to do the bulk update the day before the trip, to allow time to make sure everything downloads, and the WiFi at the hotel is reliable, the FAA didn't change anything  and everything else works.

Another problem I found, the 10.1 inch tablet might be too big for a cockpit. If I was flying an A380, it might be fine, but even in the seat in the back of the plane, occasionally it got in the way. It would be nice to try an 8 inch tablet next time. The 10.1 inch tablet is about an inch wider than my knee board on all sides. It might be nice to find a knee board adapter for a tablet. Knowing were it is, and what happens when accidentally touched might be a good thing to know. I tapped the screen multiple times on the flight, and sometimes the screen would go off center, I would have to punch the button to set the center again.

Entering a flight plan on the flight was frustrating at best. For the flights I was on, I could look at the route on flightaware.com, and see what waypoints to enter. I was on a flight from DAL to MSP, that stopped in STL. I needed to enter two separate flight plans, which would have worked much better in the terminal rather than in my seat. Then when I got done, I needed to activate the correct one. At first I had forgotten activate the first plan I entered, so the magenta line didn't show up. The Distance Next and Estimated Time Next were updating as if we were flying a single leg flight.

When we began our approach to the middle airport, I thought I could click on the approach plate, and the app would plot the current position on the plate. It didn't, which made sense after I thought about it, since the approach plates aren't always drawn to scale nor have consistent references, and SIDS and STARS never are drawn to scale. The app was smart, since it knew where we were, and punching the "plate" button brought up the correct airport diagram, and I could select the approach, SID or STAR I wanted to use.  A split screen feature might be nice, especially on a STAR.

The weather feature is nice, since it loads most of the standard weather products, (IE METARs, TAFs, PIREPS) for areas along the route. It wouldn't make sense to get a METAR for Chicago if I am going from Dallas to St Louis, and this seems to do a good job. The weather isn't updated if there is no data connection. Some apps will work with a FIS-B receiver, but even those messages may not be as timely as pilots need in a dynamic system. Talking with Flight Service is still the best way in busy weather systems.

I really enjoyed using the app. I can see it being a tool to rely on. I can also see I need to work with it a bit more, and read the manual. Other similar apps are probably just as good, and will need careful integration into any flying procedures. The FAA doesn't allow using handheld GPS devices for primary navigation in IFR conditions, but for VFR, there should be nothing wrong with using this for navigation.

What do you use?

Installing Equipment

A few years ago, I bought my wife a Toyota Sienna. It was mostly top of the line, with SatNav, CD Changer, Bluetooth, DVD player and all the bells and whistles one might want. Well, time marched on, and now the SatNav looks old. I don't use CDs in the car, I use Pandora, or MP3s that I have. The Bluetooth doesn't do A2DP, so I can't play music from my cell phone while in the car unless I plug in. The DVD player only plays DVDs, and not Blueray. It isn't even that old, but it seems my cell phone has passed it by.

Looking back to about that same time for avionics, and things have updated there as well. The GNS 430 and 530 were the top of the line radios back then. Today, we kind of admire the aircraft with those radios, but would rather have the G1000 or something newer, given a choice. How about today, well Garmin hasn't been standing still, and are ready to offer the latest better things.

What should someone do who wants the best latest avionics? I believe we are on the edge of the future. What if the (Attitude Heading Reference System) AHRS and Engine Monitor were mounted in the aircraft, but the display you could update? That would allow some lower cost better newer looking panels.

What if we could use our tablets as the display, and update the software and data over the air (OTA)?  Well today people are doing just that. Sporty's sells AHRS's that you can get today that will display the results on your tablet. Today they are only "backup", because they aren't bolted into the aircraft. I'd wager, people with these systems are using them as the primary navigation display, and relying on the less functional panel equipment as the backup.

Say you did a proper bit of engineering to mount the gyros, and added some pitot/static data. Send the data over USB or WiFi to a tablet that would also be mounted in the panel. What is the difference than a panel mount system? It will work for experimentals, and maybe part 91 operations. TSO equipment is required for Part 135, so it won't work on aircraft for hire.

It can be done, or at least something to think about. How far would someone have to go to get one of the tablet systems TSOd. I am sure there are documents that the FAA and others produce that would tell me. That will be my research of the next couple weeks.

Keep reading.

Hijacking With Android

Nope! not gonna happen. Well, not without a lot of other technology.

CNN as they are wont to do, posted a sensational article about some dude using an Android phone app to take over an airplane. That is all it is, sensational. There are some bits that could be true, but lets look at things from a more technical point of view.

Hugo Teso used a simulator to 'demonstrate' this 'hack'. It wasn't on a real airplane. The hardware he chose was not flight certified, so most of his claims are completely dubious.


First, lets get some terminology right. Hackers are getting a bad rap by this Hugo. Malicious people are crackers or criminals. Hackers are are people who repurpose technology. Think of a car customizer, someone who takes perfectly good cars and makes them better or different, they might be considered a hacker. In the pre-computer days, hackers were the folks who could do amazing things with very little. They were the folks you went to, to get things done. Places like Hack A Day is an example of a group of these folks, or the Maker movement.

An Android cellphone only work in frequencies maybe at the low end 700MHz, and if you include Bluetooth and WiFi there are radios that talk in the 2.5GHz or 5GHz frequencies. There are actually several radios covering the various modes, including Voice and the various data modes, like 3 and 4G, HSPA+, LTE, etc. They are all between about 700MHz up to about 5GHz.

ACARS is a ground to air digital messaging system. Think of it like instant messaging ( IM) from the airline operations center to the airplane. ACARs allows the airtraffic Controller Pilot Data Link Commands (CPDLC). The ACARS radios are in the 110-130Mhz frequencies. The Cell phone can't talk on frequencies that low. He would need a radio that will talk on those frequencies to talk to the ACARs device to inject some CPDLC commands. The CPDLC commands are like "turn right heading 230", the pilot must acknowledge or reject that 'command' before the aircraft will react.


ADS-B is a technology that allows the airplanes to tell each other where they are using GPS location, and a transceiver that are in the participating aircraft. The ADS-B signals are either on Universal Access Transceiver (UAT) on 976MHZ or on 1090Mhz mode-s transponder frequencies. Since UATs are US only, the dude might have gotten his cellphone to talk on the 1090Mhz frequency (although that is highly unlikely, but I don't know what brand phone he had or what radios the european version of that phone contains, it may be possible). Most of the radios in the phones aren't that programmable, and the FCC pretty much gives the 1090MHz frequency and surrounding frequencies to aircraft and not cell phones.

The Flight Management System (FMS or FMC) are the 'brains' of the aircraft. It manages the auto pilot, connects to the ACARs radio, and the initertial reference system (IRS) some of the other navigation systems. The FMS talks to the airplane. The FMS doesn't talk WiFi, so you can't just use the WiFi on the airplane to talk to the FMS or any of the displays in the cockpit (unless they have an iPad or other tablet, but those aren't connected to the airplane anyway). The FMS usually talks something like ARINC-429 and has a giant plug on it with each device having a separate wire.

FMSs can be reprogrammed, but not over the air (at least that I know of, there may be some new brand or version that can be, but if that were allowed, I am pretty sure it wouldn't allow being reprogrammed while controlling the airplane). They are finicky, and the ones in version X of the 737 can't be programmed the same way as version Y of another 737. If you want to know if Airbus and Boeing share anything, it is unlikely any of those FMSs would even share one line of code.

There is no one technology that can get this guys app to hijack a plane. You aren't going to find terrorists lining up at the T-Mobile stores to buy Android phones and downloading the app so they can take over the airplanes. Actually some might, it might be good for the stores selling phones, but folks are gonna be disappointed, and return the phones, and go buy and iPhone to be like all the cool kids until Apple comes out with that app.

We can all relax, sit back and enjoy the ride. Airplanes won't be hijacked by cell phone.