Ode to the calculators I have used...and the 41C


Well hello,

I was looking through the two large 4 foot by 2 feet by 1 foot tubs in storage full of calculators (oops, way to many, time to sell them off).

These are the non HP calculators, HP is up to 50 but the book is the reason for them. Once the book is done then a core group, say one of example of each will be saved. But that is for the future.

Looking through the tub brought to mind my HP calculator history. It didn't start with an HP though. Back in 1975 I started community college (sounds like community service) and required a calculator, in sciences so it had to include transcendental functions. New nothing about HP at the time and the office store had the neatest looking calc I had seen. This was no ordinary calc as it had STYLE. So I purchased it; a LLOYDS 333 scientific calculator with exponential display. I could finally retire the Post 1460 Slide rule!

Yep, it looked like something out of 2001, A Space Odyssey.

Well onto University (of British Columbia) for a Science degree. Started learning ALGOL W in computer science along with Fortran on the typewriter and cards. YUCKKKKK. But along with that course was the Statistics 2nd year course and they demanded and HP 25 with statistical registers:

Well not being someone that can throw out a perfectly functional calculator I removed the batteries and retired the 333. Now endless hours of Lunar Lander plus programming and etc.

After leaving university I took the HP 25 into the northern bush of Canada while flying. Weight and balance, log book times and Lunar Lander for fun...

Got back to reality in 1982 and decided to finish my remaining 2 years of a BSc but this time with money in the bank. Off to the university book store and WHOA, wait a minute, ALPHANUMERIC display with all that programming space and continuous memory and ...

The HP 41C! I purchased it second hand (2033Axxx tall keys)

Plus, after awhile I could upgrade it with x-functions, x-memory, quad memory, HPIL, card reader, laser wand, printer, plotter. So I did!. Back to work in the summers up north flying and school in the winter and fall.

Suddenly time for graduation and an offer of a Masters program. Well I jumped at the masters of Science (Climatology/Palynology) and soon realized that a more powerful version of the 41C had come out freeing up ports and it included a clock, so I removed the 41C batteries and stored it, purchased the 41CX in 1984 and wrote programs to back up the info the IBM AT 8086 had on its stacked 5mb hard drives.

In fact my 41CX did all the math and stats for the thesis, couldn't stand the desk top.

Graduate and got hired at the airline the next day. The 41CX stays with me for until 2008. In the meantime I discover the world of HPMUSEUM and start collecting and restoring.

At HCC2009 I was given an HP42S and purchased a manual for it on the drive home from Corvallis. Powells book store in Portland supplied the manual. Wlodek supplied the incentive and soon I had the HP42S with expanded memory in the cockpit:

This replaced the 41CX only because it was thinner, had sufficient stable memory for all my programs, wasn't static sensitive and still printed. It did not have a clock. I don't know why all business machines get a clock but science calcs don't. The 41CX ran multiple timers for lab processing and was fantastic that way.

Along comes 5 HP71Bs in various states of repair, the language is easy and the wow factor in cockpit is high. Of course it runs all the required programs, but size and printer requirement makes it less portable. Still it is a beauty and it has a clock! But no IR printer ;-(

So back to the 42S with the 71B as something to learn and fill in the time at hotel layovers.

Then along comes the MONTE DARYMPLE "41CL". My favorite machine is back, so out come all the HPIL and the calc is loaded with all relevant programs. A new overlay and back to work.

Thanks MONTE!!!!

Actually thanks to EVERYONE who has brought the 41 into the 21st century!!

Names like Diego, Monte, Meindert, Jeff and etc, to you I owe a thanks.

Geoff Quickfall

Edited: 25 June 2011, 8:25 p.m.


Great story for great history. Thank you.


My personal computing history was:

1969 Dietzgen 1725L Slide Rule ($35, $215 in 2011)

1972 Bomar 901B ($140, $757 in 2011)

1974 SR-50 ($120, $550 in 2011)

1977 HP-67 ($450, $1678 in 2011)

I still own these, and I could probably be tempted to sell any of them (at the inflation-adjusted price, of course). :-)

The only one that I regret buying is the Bomar.


For sheer coolness in todays LCD backlit society, the HP 67 takes the cake in the cockpit!

I do take mine with me occasionally but the 41CX/CL is the cats ass for speed and functionality!


you can just make out the 67 in the lower right corner beneath the hp 01.

Edited: 26 June 2011, 7:18 p.m.


Are these noisy EMC sources actually approved for use in the cockpit?

You aren't allowed to use your iPod during takeoff but a HP-71 is sitting on the flight computer???



Nah. The pilots can use whatever they want; the "possible interference with flight systems" was always bullshit.

With most airlines now allowing the use of iPads in place of the old Jeppson flight maps, expect this to become more common.


A few points on these.

- Shielding is wonderful until you drop your item.
- RF is not a problem unless you are sitting by the antenna.
- Aircraft navigation can be affected depending on the phase of
flight, stength of electronic, lack of sheilding and position
relative to the aircraft antenna.
- Some electronic use prohibition was probably revenue generated
later in time but originally was prohibited for reason.
- Ipad use not approved yet!

Point 1

Sheilding on older equipment was lacking or shifted or just plain useless. Note, the FAA and IATA/ICAO are reactionary, they respond to problems, develop strategies and implement them. They are slow to remove archaic rules. Lawyers and liability and laziness and all that. It is easier to ban all electronics during phase of flight then to make a list of approved electronics. The reason are money and time.

Point 2

That LLOYDS 333 will completely jam a SW and AM radio when within 2 feet of a radio antenna. Fortunately for the cockpit, the F/O and Capt radio nav equipment antennas are located over and under the passenger cabin. Also all equipment on the flight deck is sheilded for obvious reasons. Conversely, antennas are not sheilded for obvious reasons!

Point 3

Phase of flight usually depends on radio navigation and hence the antennas. That is why there is a prohibition in the cabin of transmitting devices today during takeoff and landing. High use of VHF and LW radio navigation systems of both ground and aircraft systems are used during takeoff and landing. In cruise GPS is used (different frequencies less liable to interference by RF and different attenna location).

Point 4

When phones were installed at the seats (ten years ago) they generated revenue. So the ban on cell phones for all phases of flight became a revenue thing, in part. They also had a dedicated antenna which was directional, located away from aircraft navigation antennas and again, a different frequency to aircraft navigation and communication systems.

Point 5

The FAA has not approved the battery system on the IPads and as it is new tech they have not yet tested it for use in the cockpit. They are in the process now so technically the IPad is ok but the battery is not (oxymoron?). Of course it can be stated that the public has been testing this battery for years. And guess what! Computers have caught fire in the cabin. Computers placed on pillows on the lap, plugging venting cooling fans and boom! Bad lithium ion battery batch and boom! Some rechargeable lithium based flashlights are banned from the cockpit. Happened to a fight I was on to Beijing from Vancouver. Got to tell you, at 39000 feet over the Pacific 5 hours from anywhere and the smell of smoke in the cockpit! NOT FUN. Think Swissair.

Back to the IPAD, it can be used at your discretion. This implies a liability aspect that has not been investigated by the FAA (USA). Some airlines are using it for manuals such as the Flight Operations manual, Aircraft Operating manuals and etc. The exception are Jeps which are not approved for the IPad at the at the tier one Airline level (Alaska Airlines being one but not for Jeps). They are also only used for specific phases of flight.

IPads are certainly the future for Jeps, the current problem is the only update available is manually loading the system. The FOM must be updated to include a revision provision for IPads as approved for the airline by the FAA. That has yet to be done. It is co-ordinated between individual airlines creating procedures that insure the Jeps are updated in a timely manner and that the procedure is then examined and approved by the FAA.

Annecdotal (me)

I have seen my radio nav go nuts, autopilot was not on at the time. I was climbing out of LAX to YVR (1992) going through 20,000 feet when the radio nav (VOR) started wildley fluctuating. If the auto pilot had been on the aircraft would have started a series of rapid banking (25'). After running an experiment in business class; asking everyone to turn off their computers and games. I had them turn them on one at a time. We got to a kid who had a portable nintendo hand held. He happened to be sitting right below the physical location of the #1VOR antenna. Everything went wonky (technical term) again. Business class electronic equipment was suspect as the antenna for the #1VOR is located on the ceiling right above the second row of seats.


Like any rule, law or etc the precept is based on a combination of known evidence, actual affect, probable affect, worst case scenario and etc. The rules usually apply to worst case scenarios; every one switches on the cell phone at the same time...

I still think, electronics near antennas should have a phase of flight restriction. The cost and time required to test ALL electronics on the market today is prohibitive.

As far as electronics go, during takeoff, climb, descent and landing (the so called critical phases of flight) electronics in the cockpit: NO WAY! In the cabin also NO WAY! There are still to many older electronics, older aircraft and still a reliance on radio navigation and therefore antennas.

Of course an argument can be made to retrofit all older aircraft and redesign new aircraft to allow hand held nintendos and etc. But that is a cost OR how about a phase of flight prohibition.

Another anecdote:

My airline allows cell phones on ground and during taxi. They do not in the air, of course, being me, I have tested them in the air. My analog worked perfectly as it did not due to software, limit the transmit to one tower at a time. My blackberry does lock on to one tower at a time. Because of this and at 450 KTS it has about 5 seconds of useful broadcast, just enough to tell you it has disconnected.

We were testing phones as means of communication in the event of a loss of all radios, electrics. Call ATC directly and collect the pax cell phones. Worked in the analog days and early digital (2002) but not any more.

Enough said!

HP 71B sitting on the lap Joerg, not the flight computer! And no where near an antenna. Also the wiring is shielded in the cockpit for radio aids similar to the cable tv cable and all equipment in the cockpit is sheilded. It is the passenger cabin antenna locations that are the problem.

Cheers, Geoff

OR it is all a conspiracy along with chem trails ;-)

Edited: 27 June 2011, 10:09 p.m. after one or more responses were posted


- RF is not a problem unless you are sitting by the antenna
and even then, since the antenna is outside the metal skin of the aircraft, Gameboys and other electronics of the passengers should not be a problem, except that I've seen too many situations where the connectors were not correctly mounted on the ends of the coax cable going to the antenna. If the shield of the cable doesn't make good connection, the cable itself can become an antenna too, and that's inside the plane, not outside.

Our equipment mostly goes into bug smashers and not passenger jets, but I've had quite a few times over the years when I'd get a call from an avionics shop telling me of a particular problem, and I could tell they didn't have the antenna cable connectors mounted right. They'd call back later saying they re-mounted the connectors and it took care of the problem.


Bingo Garth!

and until maintenance and etc. are perfect, this will be a problem. Until no leakage at antenna or gameboy can be guaranteed we will have restrictions.

This subject can go on forever and has only been breifly touched upon here.

Some of the problems are:

- technology takes time to be tested.
- bureaucracy takes time to react.
- procedures take time to be written.
- lawyers are involved in each step.

the last point says it all. Just look at the checklists required in the event of an emergency. Talk about gray areas!

Aviation safety is driven by the worst case scenario. Similar to bridge construction. The worst case scenario is rush hour on a bridge with bumper to bumper fully loaded semis. So after you cut the ribbon load it up with nothing but semis. Would it happen in the real world, probably not. Same with aviation, but when it happens the legal ramifications are stupendous let alone writing off a 380 with 6oo pasengers. So write a procedure that seems rediculous as it is the safer (read cheapest safest method) method.


Edited: 27 June 2011, 2:56 p.m.



Thanks - that was eye-opening!



And there are still situations were the best emergency plans and safety measures simply fail. :-(

In most, if not all, cases the situation simply wasn't foreseen by the authors of the procedures.



very astute, simply put, all air regulations have a basis in an accident or incident;

each pilot consumes a different meal originating from a different kitchen,
seafood is not served to pilots
arming disarming doors,

the list goes on.


Edited: 27 June 2011, 6:45 p.m.


I like to tell people that any fool can build a bridge that will stand up. The trick is building one that won't fall down....

It's true that some problems are unforeseen by the engineers, but I think more often trouble occurs when a combination of problems happen at once. It's really hard to figure out how to deal with those cases. I suspect that the airline industry in particular has reached this point. More airline accidents today are probably the result of multiple simultaneous failures, not a single problem.



and even then, since the antenna is outside the metal skin of the aircraft

But, the skin is full of holes (windows!), all of which act like slot antennas (just as good as a dipole: a slot in a sheet of metal is the inverse of a dipole in free space and works just as well to re-radiate any electronic racket generated inside the passenger cabin).

If you want good shielding, you can't have any breaks in the surrounding metal (holes less than 1/20 wavelength or so might be ok) - just ask NSA, who shield some of their entire buildings to keep external prying eyes (ears!) from listening to what goes on inside.

While the likelihood of interference is low, I'd rather be on the safe side.


But, the skin is full of holes (windows!), all of which act like slot antennas (just as good as a dipole: a slot in a sheet of metal is the inverse of a dipole in free space and works just as well to re-radiate any electronic racket generated inside the passenger cabin).
Yeah, then you can get into fresnel zones and all that-- but due to the curvature of the fuselage, there's nowhere near a line-of-sight path from the windows to the antenna. When I have the techs in the avionics shops fix the connector terminations, the problems are totally gone-- and this is on small aircraft whose windows are very large proportional to the size of the roof or belly. (For the record, I've worked in VHF & UHF power transistor applications engineering, but not antennas. I have some feel for antennas from being a radio amateur and also high-speed digital design.)

Edited: 27 June 2011, 7:47 p.m.


But, the skin is full of holes (windows!), all of which act like slot antennas (just as good as a dipole: a slot in a sheet of metal is the inverse of a dipole in free space and works just as well to re-radiate any electronic racket generated inside the passenger cabin).


While the likelihood of interference is low, I'd rather be on the safe side.

Are two extremely salient points to keep in mind

Thanks Dave


IPads and computers have caught fire in the cabin. Computers placed on pillows on the lap, plugging venting cooling fans and boom!

Computers, perhaps; iPads, never.


Sorry shouldn't have included the Ipad, although one crew dealt with an extremely hot IPad, defective battery.
They isolated in the galley until it cooled. It did not work afterwards.

As stated earlier, the FAA is now testing IPad batteries.

statement edited.

Cheers, Geoff

Edited: 27 June 2011, 10:11 p.m.


I could finally retire the Post 1460 Slide rule!

The thing that got me to retire my Post 1460 was Teledyne-Post 44CA-600. And I still have one sitting on my desk.


I carry my post 1461 with me as back up and boredom stopper!


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