View Full Version : Plugging laptop into 747 airframe power

25th Mar 2002, 02:39
I'm not talking about those new seat-side 12-16 VDC adapters in business and first class. On the upper deck of a United trans-Pacific 747 flight, I observed a passenger plug a laptop computer AC adapter into an airframe socket near the floor next to the left-side exit door. (You have to lift up the cover to get to it.) I think the socket said 110 volts and 400 Hz. While these computer adapters can go from 100-240 volts, all the ones I have seen are rated for 50-60 Hz. Made me wonder because capacitive reactance goes down at higher frequencies, and inductive reactance goes up -- but, I don't know what all goes on in those adapters. Thought it might be a possible safety issue but the passenger and flight attendant did not seem too concerned.

25th Mar 2002, 03:18
Dont know about UAL specifically, but that sounds like the electric outlet for the cleaners to plug in their vacuum cleaners etc. The outlets are on the ground handling buss from external power or the Nr 1 APU generator, and therefore not usually powered in flight. Not to say they couldn't be, just that 747's I've worked around weren't configured that way. Its 115 volt, 400 freqs power so I dont know how it might react with a 110v/60cycle transformer.

25th Mar 2002, 03:21
There is a similar plug in the cockpit of many airliners 320s 300s and 727s from personal experience. Many times I have plugged my laptop or my cellphone charger into those plugs with no bad effects.. .. .In all cases the powersupply converts the power to DC which doesn't have cycles so it shouldn't care whether it is 60 hz 400hz or 4 million hz.... .. .You wouldn't want to plug an your hairdrier in however has it would run at 8 times the normal speed..... .. .Cheers. .Wino

25th Mar 2002, 04:00
Get your hair dry rather quickly though!

Continuous Ignition
25th Mar 2002, 04:19
Yep, I also have used the outlets in our old DC-10's and B727's to run my laptop with no ill effects.... .. .And I have seen the cleaners try to use a standard vaccum in those outlets once or twice too.. .. .The bloody thing spooled up like a JT8D-217 going to takeoff power for about 10 seconds till she smoked her guts out... . .. .Pretty funny stuff for sure! Although the cleaners would beg to differ...

25th Mar 2002, 07:58
IT WORKS!! Those outlets are used for doing the hoovering, but are supplied by the ground service bus, which is normally supplied in flight. Yes they are the wrong freaks, but yer average portable electronic device runs on d.c. and requires transformation. Now, getting the hostie to let you use it is another thing...

25th Mar 2002, 14:12
Personally speaking, Eboy, I wouldn't let passengers with laptops go anywhere near those power points. They are used for a variety of medical reasons in flight. If you go messing with them, you may be putting the health/welfare of sick passengers at risk.. .. .Worst case scenario: If your computer equipment was faulty, it might blow the circuit breaker(s) in the Main Equipment Center. This is located below the main passenger deck and is not always the easiest things to access in flight. If a sick passenger was constantly using some kind of medical device at the same time you may end up killing him/ her in the time it takes to get to the CB. . .. .Sometimes a passenger brings his/her own medical gear for use during the flight... e.g. a ventillator (for asthma) with a suitable transformer.... A list of approved types is given to the passenger, but sometimes signals get crossed and the passenger brings the wrong sort. In this case, the passenger is usually prohibited from flying (or from using the device... and proceeds at his/her own risk). BTW, incorrect transformers make some really disturbing high pitched buzzing noises (as many can't handle the high frequency). Your laptop transformer should specify the range of frequencies it can handle, but this is, in no way, an authority to use it on an aircraft.. .. .As Jetboy says, the power points are provided by power from the Ground Service Bus which IS powered in flight (as opposed to the Ground Handling Bus).. .. .Be advised.. .. .Rgds.. .Q.

Flight Detent
25th Mar 2002, 15:46
Good on ya, Jetboy,. .You are quite right, Ground Service Bus, powered from the AC bus #1, in flight.. .Cheers!

25th Mar 2002, 19:33
We use them for people who need them for Aspirators or such like, people who suffer from Asthma. There are certain types of aspirators that are the only approved type for use on a/c, you can't just plug your home one in for obvious reasons as stated above.. .Things have to be approved by the reulatory bodies you can't just go around plugging things in. <img border="0" title="" alt="[Eek!]" src="eek.gif" />

Willit Run
25th Mar 2002, 20:46
400 HZ won't hurt a transformer for your laptop. We've been using the ones on the Tri-Star and the A-300 with no ill effects for laptops and cell phone chargers. These things just keep on tickin!

25th Mar 2002, 23:58
Our loadmasters have been using ships power for several years to power their laptops and printers with no ill effects noted. We are now installing computer work stations on the upper decks with dedicated power plugs using ships power. (115vac 400mhz). One of our guys told me that when he deadheaded on an Asian carrier recently, they had standard type plugs at the seats instead of power port. I have to agree with Qavion about using plugs not specifically approved for laptop use, but some pax just do it anyway and most F/As are reluctant to make them unplug.

26th Mar 2002, 23:17
Following all statements above, I wonder why those plugs can't be neutralized once airborne ? (unless some medic devices needed). .If any "side effect" suspected, it shouldn't be very expensive & complex to cover those plugs with carpets or simply lock them ?

1st Apr 2002, 13:55
I fly the B767. In the cockpit there are a couple of sockets which pilots use for their laptop usage. Questions:
1. What are the manufacturer recommendation plugging in Laptops on the B767. Also the Airbus aircraft?
2. What Laptop procedures do you have?
Safe Pluggin's

1st Apr 2002, 20:38
1. There's more that can run down and around a circuit than the electrical current that it was designed to carry....inductively or otherwise. Always remembering TWA800 and United 811, you could say that the Law of Unintended Consequences can strike wherever it wishes. So, if I was a terrorist looking to damage the aircraft's electrical system via plugging into it...... what are my chances of success:
a. in FBW?
b. in non FBW?

2. If I were to utilise TASER/ stun gun type technology with high spec/heavy-duty capacitors what would the effect be upon the aircraft for a discharge:

a. via the power port/receptacle (of types various)?

b. into the electrical system(wiring bundles) elsewhere (say, within the unobserved confines of a lavatory or in the galley area)?

3. Would I need a large battery for my device - or could I just plug it into the aircraft power supply to charge up its capacitors?

4. Now I know that an aircraft is well-bonded, sheds external static charges and is an effective Faraday Cage against external HIRF, lightning strikes etc - BUT, being on the inside of the fuselage, can I (as a terr with the right piece of kit) damage the aircraft electrical system either overtly or covertly?

5. What could be the extent of such system damage?
a. blown breakers and fuses?
b. tripping gens? rebooting computers, fried CPU's, soldered relays, zapped solenoids, diddled diodes, clean-screens ?
c. destruction of sensitive electronic components?
d. electrical fire?
e. intermittent "faults"
f. antenna coupler burn-outs?
g. exploitation of frequency sensitivity of certain equipts
h. comms disruption
i. RAIM outages of the GPS, transponder outages
j. EGPWS/TCAS false alarms
k. bus sensing/switching faults
l. etc etc

6. Are there "currently" (within a/c systems) any CPD's designed to obviate such non-accidental damage? Thermally tripped CB's may not act fast enough to obviate damage (is my point).

7. Are there any particular systems more vulnerable than others?

8. If I had particular aircraft knowledge, could I access vulnerable wiring (i.e. wiring not associated with IFE, galley or seat-provided power-plugs)?

9. Before answering, just remember that aircraft designers use the fact that airplanes have to be 100% well-bonded through saving wiring weight by utilising the metal fuselage as an earth return. This "short-cut" introduces is own problems of course (in the form of system intermittencies and non-reproducible faults that might not otherwise occur) - but it possibly also provides yet another vulnerability (to electronic attack).

10. The reason I ask this is that:
a. Airbus was posed these questions by a journo mate (at my instigation) and proved to be both evasive and hostile (to the point of no further correspondence). It came up in the context of the possible use of stunguns and TASERS - and the unintended consequences of connecting with the aircraft versus the bad-guys.
There may be nil vulnerability - but vertical fins were never supposed to fall off either. It may well be deftly avoided on the grounds of "security", or they may just lie about it - however it might be more appropriate to just answer the question and if there is a vulnerability, finding out about it before some Al Qaeda "wise-guy" answers the question for us.

b. the FBI is aware that a gent with a M.E. type name has been asking similar questions. How do I know this? The gent's emailed query was reported to them.

1st Apr 2002, 23:14
Unctuous... you are not planning anything are you? You are surprised by how Airbus reacted? They should have sent your friend a complete overview of how to kill the Airbus electrical System? Or were you looking for "Airbus Terrorism for Dummies (part3)"?
Come on, get serious. I don't know an answer to all of your questions, but the few answers I do know... I'm not posting them here! SORRY...


Dagger Dirk
3rd Apr 2002, 14:30
If the guys with the M.E. names are already asking these questions and coming to the attention of the FBI (who just wouldn't know how to look into it further), then it would be responsible to, as the parliamentarians say "put the question". Only in this way will security be assured. But then again one wouldn't want to end up like these guys:


American Airlines harassing pilots for speaking out, pilots' union says

So Pegasus 77, as an A320 pilot maybe you should conscionably pose the question to your superiors, as it would seem from your reply that there may well be something to be concerned about. The reason why the Terrorists were so successful on 11 Sep 01 was simply that the regulators and legislators were wilfully blinkered in that they decided to take risks. With the benefit of hindsight they now desperately wish that they hadn't. However with hindsight there's also nothing so obvious as the statement that not looking into security vulnerabilities is almost a death-wish in itself.

3rd Apr 2002, 21:23
Would make sense forwarding these questions to for instance our technical department; I hope when receiving those questions, Airbus, although not answering, took them serious.

I'm not concerned about anything specifically. An Airbus, (and let's not forget the 777, which is all FBW as well!) is a sort of flying nintendo, and even when protected with fuses, a Nintendo turns to toast when blasted with idunnohowmanyvolts.

I think it is interesting to explore all kinds of ways to commit terrorist acts, because, as is succesfully proven on sept 11th, you never know what a terrorist might come up with. And indeed maybe the next terrorist will be having a pacemaker, with a nice little battery, which, when plugged in the electrical net, blows up the avionics.
To that I only want to add: you don't want to present the outcome of such research on the internet. Why give a terrorist all he needs on a silver plate?