Don your hard hats!!

[seagull2200]

I'm sure this will attract at least 50 different views but here goes..

I used to fly with ATC and seeing my first Pilot at 13yrs of age, adorned with his helmet, gloves and suit was awesome - i thought HE was God - in a sense i suppose he was!

Fast forward 15yrs, and here i am, part way through my PPL. Sometime ago, i decided to invest in a flying helmet and gloves. NOW. - I'm going to be absolutley honest about this..

1) I've always wanted my own helmet, and yes, i do think they look cool - but PLEASE 'Hold your fire.....'

2) I got the helmet, and in so doing did some research - this is interesting:
i. App 93% of light a/c fatalities are due to the head impacting the dashboard / instr.panel
ii. APP 98% of THOSE fatalities would have not been fatalities had the crew been wearing helmets.

3) The whole reason i'm learning to fly is to (hopefuly) get a position with Mission Aviation Fellowship (MAF). All MAF crews HAVE to wear helmets at al times on flying duty, so i thought it'd be good to get used to the idea early on.

I took a number of flying lessons, and decided to wear my helmet on a couple. The response from the instructor was quite negative. He simply didn't want me to wear it - he stated he found it a bit difficult to communicate with me when i wore it. (Can i just add that this is a very plain white Alpha 200 from Headset Services at Shoreham, not some 'Tiger Meet' or 'Top Gun' style thing).

This was after one occasion when we had jumped in the Cessna 150, ready to Pre start-up checks and found my helmet, for some reason, wouldn't work with my instructor's headset - this got to the point where my instructor dvised i forget the idea, go and get a 'normal' headset from the flying club portakabin, and start again. This i did, to find when i got back in, the instructor 'suddenly' realised he had forgotten to flick a swith on the radio, and now everything was fine!

Sound sceptical don't i? I'm aware i'm in learned company, and extend full respect to all (instructors especially) who are reading. However, with the greatest of respect i would like to share some of my initial observations of the Light Aviation contemporary culture.

1) When asked why we don't wear parachutes, i was told that, you never fly high enough for the canopy to develop, and i'm supposed to 'go down with my ship' as it were, to avoid impacting towns etc, and that these things 'never happen'
- "Oh really??" Try telling that to the 2 pour souls who perished in Liverpool Bay just last Sunday. Also, parachutes are used by base jumpers from less than 200ft.

So, although surrounded by well meaning souls advising me 'Whilst in Rome do as Rome does...' I'm afraid i remain unconvinced. The forces can fly Grob Tutors with masses of safety equipment - and very well too. Should i be replying to my instructor that, at 29yrs old i'm very able to decide what i feel is safest for me to protect myself. Seriously, if i'm paying £95 for a flying lesson, have invested hundreds in my safety, should i lay it all aside because a flying instructor doesn't share the same concern for him/her to invest in their own safety as i do, and feel 'a little uncomfortable' with me wearing mine??

Can i ask, if all the professional organisations, such as aerobatic flying schools, Police forces, Air ambulances etc.. all see fit to protect their crews - why shouldn't i?

As you can sense, i'm a little 'scraped' on this topic of safety - i just feel that, relying on a (albiet well serviced) SINGLE old engine (which i'm sorry - but at the end of the day that's exactly what it is!) to get you across expanses without facing upto, and preparing for bad eventualities, is foolhardy and downright unprofessional.

So here's the punchline: Yes, it would cost a lot, but i value life, and acknowledge the frailty of man's machines too much, and their absolute ability to go wrong in spite of rigourous servicing (speak to NASA). If i had a flying school, i would require an OPEN and ACCEPTING - if not encouraging approach to members wearing helmets, chutes, even nomex flame proof suits if they deemed necassary.

Ok, i bow out to retreat to my trench in readiness for the response.....

Yours with great respect to all.

[bar shaker]

Seagull

Its a very well put argument.

I suspect that many ppls have done a track day in a reasonable motor. You simply are not allowed on the track without a fastened helmet. The reason is that there is a chance that you may crash and your head should be protected from the hard surfaces around it.

With so many fatalities in the last week+, your post is thought provoking.

bs

[VP959]

First off, it's really your call as to what you choose to wear, but it's worth taking into account all sides of the safety argument.

Your statistics sound a bit off to me (and I have nothing against helmets BTW, having spent the vast majority of my flying time wearing one). As well as protecting your head from impact, the helmets extra mass will also add to the inertia of your head in a sudden decelleration. This will increase the risk of you suffering neck injuries considerably, and neck injuries have featured fairly often in the accident stats.

Your instructor also has a say in this. He is captain of the aircraft, so has the perfect right to tell you what is acceptable to him or not. He may well be concerned that your helmet is more likely to cause him a head injury in any incident, as an example as to why he feels it's innappropriate.

Finally, I worked on the design of parachute systems for many years and there is no way on this earth that a hand deployed parachute will deploy and decellerate a human body to a safe speed when exiting an aircraft at 200ft. I've done a low level forced deployment static line jump and even at 400ft, with the parachute literally forced out by the deployment sock, it only just had time to get me to a safe speed before hitting the water. It's also very difficult to climb out of an out-of-control light aircraft, and if it's in control your chances of survival are better from doing a forced landing.

Anyway, having said all that, the vast majority of accidents occur when taking off or landing, so a parachute wouldn't actually make much sense in a normal GA type.

If you're doing aeros, where loss of control or aircraft failure at altitude is far more likely, then I can see the merit in wearing one. Similarly when gliding, where you are deliberately flying in close proximity to other aircraft, often in pretty turbulent air.

[Paracab]

A very interesting point, and something I have often thought about.

At the end of day it will always come back to personal preference and what risk is acceptable to the individual.

Obviously, helmets are worn in other fields of aviation due to the increased risk associated with them - for example air ambulance ops, where landing in unassessed sites is the norm, and clearly carries with it an inherent risk, so helmets are mandatory.

As for wearing one in your situation, personally, unless your instructor has a valid argument for you not to wear one, I think it should be your choice.

[bar shaker]

Hmm... your instructor is concerned about your helmet causing damage to his head. He would prefer that your bare head caused the damage?

VP's point about inertia is important. Mil helmets are normally kevlar. Very light and very expensive.

The point is still good though.

[TonyR]

seagull2200

"I got the helmet, and in so doing did some research - this is interesting:
i. App 93% of light a/c fatalities are due to the head impacting the dashboard / instr.panel
ii. APP 98% of THOSE fatalities would have not been fatalities had the crew been wearing helmets".

I am not sure where you got this from, seems a bit off to me.

In a previous life I have worn this kit, I have also seen what a sudden stop from high speed can do to a body and trust me a bone dome will do nothing to save you in all but the lightest crash.

I saw a microloght crash about 4 years ago and it would not have mattered what they were wearing as the result was their bodies being ripped apart by the harness and as they only were at 500 feet they would have had no time to jump.

If you do wear a bone dome make sure it is a very light one as you don't want to give your already heavy head more energy to help it rip itself from your neck.

Better to keep up practice at PFLs and pick your route to give you a better chance of putting it down somewhere flat.

To be honest I feel much safer in the air than I do on the road and I would not wear your top gun kit in the car

Tony

[maggioneato]

Seagull how right you are, I am as guilty as anyone for no thought about what attire to wear to fly. I just wear the same things as I wear to drive my car. It's not down to cost, flying is an expensive hobby, so it must be not wanting to be on the receiving end of sniggers and such about wearing a bone dome in a C150. Stick to your guns, you are the paying customer, as long as there is no communications problem, and you are comfortable with it, wear it, and hope you never have to say, thank God I did. :p

[MLS-12D]

First off: don't worry about what other people think. Some swear by helmets, while others swear at them (i.e., think that they are stupid). Decide which camp you fall into, and act accordingly.

Secondly: VP959 is quite correct: your instructor has the right to decide whether he will fly with a student wearing a helmet. However, you also have the right to decide whether you want another instructor (it's your money).

Thirdly: I am not all that suspicious about the fact that your instructor missed a switch ... we all overlook such things from time to time. Okay, an instructor is usually flying often enough that he shouldn't make such mistakes; but if he is jumping back and forth between different airplanes, it is easy to get confused with the different radio arrangements.

Finally: I don't buy the reasons given you as to why parachutes are not worn:

(a) "you never fly high enough for the canopy to develop". I don't know what the practices are at your flying school, but personally I always fly above 1000' agl, which is plenty of height for an emergency parachute to deploy;

(b) "I'm supposed to 'go down with my ship' as it were, to avoid impacting towns etc.". Call me selfish, but I'd like the option of saving my own skin; especially since if you have a situation meriting a parachute escape (e.g. a structural failure, or a serious fire), you will have little or no control over the aircraft. In any case, personally I don't do much flying over towns;

(c) "these things 'never happen'". Oh, really? Any one who has been involved with aviation for more than a month knows that midair collisions do happen.

The real reason that parachutes are not commonly worn is that most contemporary general aviation airplanes are designed in such a way that it is almost impossible to bale out (you can wear a chute in a PA28, but will it do you any good?). When I fly an aircraft designed for rapid egress (gliders and Harvards, specifically) I always wear a chute. IMHO, not bothering with such safety gear is no different from deciding not to fasten your shoulder harness (because "it's too restrictive", or some other silly rationale).

As for wearing one in your situation, personally, unless your instructor has a valid argument for you not to wear one, I think it should be your choice.Exactly.

[Flock1]

I agree, what an interesting thread!

When I first read the title of it (and then clicked on it) I was ready for a good laugh.

But after having read through the coherant arguments put forward by Seagul, I shall follow this thread closely.

Flock1

[astir 8]

People used to be mocked for wearing seat belts in cars (my ex-RAF uncle was one of the mockers). Cycling helmets used to be regarded with similar distain.

Both are now common and/or compulsory, ditto airbags, so it will be interesting to see how things progress in the aircraft industry.

Something more restraining than those pathetic lapstraps in the average GA aircraft would be a good start

[GARDENER]

Having been fortunate enough to survive an "aviation accident"....won't bore you with full details, the only damage I sustained was to my head! Knocked myself out and was lucky not to have Bendix King tattoed on my head. I do have a scar on my head as I needed 12 stitches, to get to the point had I worn a helmet I would most probably have climbed out of the wreckage myself rather than being assisted. Still do not wear one but yes it's a good idea.

[boomerangben]

I started my flying without a helmet and I know wear one all the time. I would feel naked without it.

I would seriously consider changing your instructor or flying school. Your reasons for wanting to wear a helmet are perfectly valid (even if the stats are debateable). Also they provide better noise attenuation, have built in sun and clear visors and you can get little lights to stick on them for night flying.

The only down side with a helmet is that they get hot and sweaty.

[majorcan]

I don't care what you think he sounds like, everyone is entitled to their own opinion and yours, whatever you think, is not really valid on our forum.

If you want to diss someone, please do it via a PM or something, there is no room for comments like yors on our forum.

[FNG]

The prevailing culture in a sport can change. Thirty years ago your riding instructor might have teased you for wearing a helmet. Not now. Five years ago your skiing instructor might have teased you for wearing a helmet: not now. Nowadays I wear a flying suit, a light plastic helmet, gloves and a parachute and don't care what people think. Both of the aeroplanes I fly regularly have jettisonable canopies rather than doors, and, as one used to belong to the Armee de l'Air, and the other to the RAF, I don't feel too daft getting in and out of them wearing flying kit, but I confess that, if I flew a Cesssna, I might dispense with some or all of the kit. There's not much logic in this (apart from the difficulty of abandoning that type of aircraft in flight).

[Lowtimer]

I also wear a helmet in aeroplanes that seem to call for it - Moth, Pitts, Yak, T-67, Cub etc., and at Northants School of Flying if you want to fly anything open-cockpit, you'll be doing so wearing a bone dome. I don't wear it in a PA-28, but that's mainly because I don't have enough headroom clearance in it. If anyone wantsto have a snigger, they're more than welcome, and I'll carry on doing it the way I see fit. I use the DC K series - it is pretty compact and light.

[ozplane]

I think I read about somebody developing air-bags for light aircraft. Too late for the geriatric C150s and PA-28s but maybe do-able by the more enlightened manufacurers like Cirrus. This might ease Seagulls fears of impact with the dash panel. The other approach is to make the safety kit less obvious. A firm at Aerofair were advertising life jackets concealed in a normal looking windcheater. This seems to me a good solution for those fliers who don't want to look like a wimp on the trip over to Sandown. A helmet might also be useful if the aircraft comes to rest inverted. I gather there have been people who have been injured by releasing their belts and falling on their heads due to disorientation.

[big.al]

Interesting post this. My initial thoughts were 'no, I wouldn't want to wear one in our C172'. But then again (without wanting to pre-empt the official accident report) the recent incident at Lundy involved the pilot being pulled from the wreckage by bystanders because he had been 'knocked unconscious' (so I understand). The following fire destroyed the airframe, and had it not been for those brave souls who helped him, the pilot would have suferred the same fate.

I don't know whether wearing a helmet would have prevented the unconsciousness - perhaps the eventual report will tell us more - but it does suddenly make me think that there is more to the idea of wearing a helmet than my first reaction....

As an aside, linked to another thread, those people at Lundy who rescued the pilot deserve every medal we can give them.

[Vedeneyev]

I too was ready for an 'epaulettes' style thread but hey...

My opinion is that this all stems from when Mr Cessna and Mr Piper amongst others decided to design massmarket aeroplanes around the niceties of the car - big armchair seats, inertial reel seatbelts, ash trays in the door, steeringwheel-like yokes etc... Aviation from that point was marketed not so much as a sport, but a practical everyman's mode of transport. Wearing a helmet not being so practical in either everyday car use or everyday cessna use.

Not sure where the stats in Seagull's post come from but I have to admit that the only injury in the one crash I've witnessed resulted in the non-helmet wearing occupant receiving stitches to the head....

I guess it's the same argument as not wearing a full immersion suit on a lunch hop to Le Touquet - probability and practicality would be on your side, but one shouldn't be derided if you chose to plan for the worst.

[pulse1]

Presumably, anyone deciding to wear a helmet in, say, a C172 would also have to provide them for any passengers? Variations in head size could be a bit of a problem.

[robin]

I think as said earlier, one issue is of quick exiting from aircraft. I've never understood why the door on a PA28 is on the passenger side.

Seems to be a certain death for the pilot. Why they couldn't have put in on the pilot's side escapes me.

If the passenger gets incapacitated the poor pilot is stuffed, and in solo flight it's a struggle to move across

[MLS-12D]

pulse1, I don't see why a helmeted pilot of a multi-seat aircraft would be duty bound to provide similar headgear for all passengers. Helmets are very expensive, and (IMHO) to work well they have to be custom made, or at least fitted with a semi-custom liner.
It would be nice if everyone could have a helmet, but I wouldn't refrain from wearing mine just because a pax had none: my greater safety doesn't adversely affect his (now parachutes, that's another matter).

[dublinpilot]

Well I'm sure FNG would be better able to comment on this, but I imagine that if your personal risk assessment concluded that the risk was significant enough to warrent the wearing of head protection, then, as you owe your passengers a duty of care, you would be required to give them head protection too. To do otherwise would apprear negligent.

If you didn't and they suffered a head injury that the protection could have provented, or reduced it's severity, then I think you'd have a hard case justifying why you saw the need to protect yourself, but not your passengers.

dp

[Wide-Body]

I think Seaguls statistics are slightly out, however his sentiment is not. The original pink aic quoted, 80 percent of accidents involving fatalities or serious head injuries would be avoided with appropriate head gear. The latest aic Pink 175(101/98) states that 5 DEATHS would have been avoided if helmets had been worn. For commercial pilots the CAA will suspend your licence for a considerable time as a result of a head injury.

Pulse 1. Alpha make a pax helmet that is designed to fit varying headshapes.

Parachutes, I use Russian chutes, bloody heavy but will low altitude deploy 500ft (just ask a Sukhoi 26 pilot in Spain. FNG has it spot on, the practicality is in being able to leave the a/c. Doesn’t the Cessna 150 Aerobat have jettisonable doors. As for getting out of a normal aircraft in a chute, is probably pointless.

As in most of flying, safety equipment is a matter of risk management. As I fly older or aerobatic aircraft (Chipmunk-YAK) I wear Kevlar Bonedome, nomex flying suit and gloves. I also don’t tend to flyover large stretches of water. However I am a big girls blouse.


As in all of these cases, present the facts and let the adults make the decision.



Regards




Wide:ok:

[MLS-12D]

Dublinpilot, you are correct, at least to the extent that there is an argument to be made.

However, an argument can also be made that everyone benefits when a pilot's safety is increased (if he or she is incapacitated - which can happen in circumstances other than a crash landing - who will fly the aircraft?). It is hardly unique for aircrew to be furnished with better equipment than their passengers. E.g., the pilots of most (all?) commercial airliners have much better safety harnesses than the crummy lapbelts back in the cabin, and (I believe) air ambulances do not typically provide their patient-pax with helmets.

In any case, personally I wouldn't let the possibility of an adverse finding in a potential lawsuit prevent me from wearing safety equipment that might save my life ...

[IO540]

seagull2200

I haven't read the entire thread (not enough time) but I think there is little point in wearing a helmet in a normal GA type in case of an accident.

If you have an accident during a deliberate ground contact (i.e. a landing) then usually you walk away from it. The plane might get wrecked but unless somebody does something drastically bad they are usually OK.

If you have an unintended ground contact, that is probably flying into a hill in poor visibility or in IMC, and at say 100kt a helmet will make no difference, because the plane will be obliterated.

I do know one man who went into a hill in IMC at (he says) about 120kt, at such an oblique angle that he just ended up in hospital for a while. But that is a one-off.

If you want to wear something, spend your money on the very best headset you can buy: a Bose X :O

Otherwise, spend it on the best GPS you can buy. <--- that comment will make this thread run and run, but I am getting out of here!!!

[FNG]

I kit up to counter the dangers posed by (1) impact to head in forced landing or in aerobatics/spinning ; (2) fire aloft or on the ground; (3) structural failure in flight, and (4) a survived midair (I do not wish to spend my last few minutes alive as a falling leaf). I offer my passengers flying kit and a chute, not so much from a risk assessment/duty of care point of view, but because it seems rude not to (although I'm a lawyer I definitely do not live my life by reference to risks of law suits. Most of the health and safety excesses of the kind deplored by the whinging lawyer-haters in Jetblast are not in reality lawyer driven).

Last Sunday, I meant to take my lifejackets to cross the Solent, but forgot to pack them. In the event, we had to cross at 1000 feet so could not have glided clear if the engine had failed (one Bulldog minus one engine equals one brick sh**house with wings). Some of this safety awareness blah may be down to experiencing the unexpected but happy prospect of fatherhood in middle age: if I die, my wife is well covered by my insurance, but I would like to meet my kid.

[seagull2200]

I'd like to thank very much everybody (With the exception of one individual..) for the replies to this thread

This was my first thread, i joined just last night, and i'm pleased with the valuable and varied insights which have been extracted from this topic.

The helmet i have is a reconditioned ALPHA 200, which was slightly more expensive than a good motorcycle helmet. It's construction looks to be of carbon fibre, but it is much much lighter than a motorcycle helmet. As for the added weight in respect of inertia, this is something i admittedly had not thought about previously.
I suppose with use, such as the heavier motorcycle helmet which felt like lead when i passed my motorcycle test, i would reach the point where i wouldn't even realise i'm wearing it. Today, a motorcycle helmet is for me just like wearing a cap, seems your neck / reactions adapt in time to the different pressure and muscles requirements to ensure when you 'slam-on', you don't konk your head on the windsheild.

I totaly understand the strange concept of wearing safety gear whilst flying the air- equiv of a Mondeo (PA-28 Etc), but as for it being nigh-on impossible to get out of a light aircraft which is out of control - call me stupid, but i would be willing to give it my best shot in an emergency, rather than decorating the local farmer's feild with a 'Chris & Cessna' fuelled bar-b-que - provided of course i had a 'chute!

Q) So what have i learnt from all your responses for which i am grateful?
A) Without wanting to sound smug, i think the last paragraph of my initial mail has been underlined. That being that people have different views - some like helmets, some don't. Some see that level of safety equipment necassary, some don't - some feel in certain types of aircraft, some in all, some in non.

So, are we surprised at the responses? I think not - What i do think is that these responses call for people such as me and you, especially where safety is concerned, to have the right to raise our safety measures to the level at which we see fit, and in doing so, not being discriminated against in any way. Also, that we, in respect of others, would embrace an open and accepting attitude in regards to this.

Thank you so much to everyone - and may this first thread never have to be brought to the fore in an emergency for any of us.


Very Kind regards

Chris W (Helmeted-Seagull2200)

[MLS-12D]

Although I'm a lawyer, I definitely do not live my life by reference to risks of law suits. Most of the health and safety excesses of the kind deplored by the whinging lawyer-haters in Jetblast are not in reality lawyer driven. As usual, we are in complete agreement.

I offer my passengers flying kit and a chute, not so much from a risk assessment/duty of care point of view, but because it seems rude not toI would certainly offer a passenger a helmet, parachute or whatever, if available. Indeed, I'd probably insist that they avail themselves of all safety gear ... it's just common sense.

Notwithstanding the above, honesty compels me to admit that I rarely wear a helmet, although I do own one. :O I don't really have an excuse; it's just that usually I can't be bothered to lug it out to the airport (one more bag to carry), and it can be uncomfortable on a hot day.

[Evo]

I wonder how much of the head injury problem is caused by the car-style seatbelts and cr@ppy seats in the PA28/C172 style aeroplanes? Excluding aerobatics, as IO-540 says a bonedome is only going to be any use in a low speed accident - which almost by definition is one during take-off or landing (forced or otherwise). Wouldn't it be better to make sure that the seat and harness stop your head from getting anywhere near something solid?

The seat rails in the PA28s I used to fly seemed very flimsy (and by reputation the Cessna ones are worse), and I would be surprised if they stopped the seat sliding forward if you hit something solid. Likewise, the three-point seatbelt is total rubbish - there was one poor sod in the AAIB reports recently who flew a perfect forced landing after engine failure only to die from head injuries thanks to the seatbelt being useless when he hit something after landing. I've even flown an aeroplane (once) with just a lap-strap :rolleyes:

[Saab Dastard]

The answer to the problem of increased inertia with a helmet has been partially addressed in Formula 1 with the introduction of the COMPULSORY helmet restraint system.

Possibly too restrictive for aviation (at least for those who want to look out the windows - that's another thread), but some modification might still be appropriate.

2P

[FlyAnotherDay]

The response from the instructor was quite negative. He simply didn't want me to wear it - he stated he found it a bit difficult to communicate with me when i wore it.
Your instructor's attitude is 'interesting'. He doesn't seem to have accepted your preference to wear a helmet as valid, nor does he seem to have made a reasonable effort to convince you that that you not wearing a helmet was the safest option overall.

There's a relevant thread (http://www.pprune.org/forums/showthread.php?threadid=110753&perpage=15&pagenumber=1) on Rotorheads, although it's helicopter-oriented.

Hearing protection and reducing the chances of fatal and non-fatal injuries, particlularly following forced landings and birdstrikes, are valid reasons for wearing a helmet.

Increased neck-loading in accidents is a reasonable concern, but I've found no evidence to weight the argument against helmets (I don't mean there isn't any, I'd like to hear if there is), whilst there is a wealth of evidence to support the use of helmets in light aircraft operations.

Communication incompatibilties should be sortable either with the help of an avionics engineer - or with a different instructor;)

[seagull2200]

Just to put a smile on your (helmeted) faces...

http://www.fototime.com/347803C8C20216E/standard.jpg

:ok:

[MLS-12D]

I've said it before, but I'll take the opportunity to repeat myself on this thread: everyone who flies an open cockpit airplane or 'warbird' should splurge and purchase a Campbell Aero Classics (http://www.campbellaeroclassics.com/default.htm) helmet. Much classier and authentic than those Gentex things, unless of course one happens to be flying an F-16!

[map5623]

I must admit to flying a Pietenpol with my motorcycle gear on, including the helmet. My thinking was that if something hard came my way it might help, also it did keep the wind out and my head warm.

Mike

[Capt. Manuvar]

I think the benefits of wearing a helmet in any form of aviation outweigh the risks by far. But there is the issue of personal image, i think younger people tend to want to look more "flash" and while the older middleaged types try to tone down their appearances, except when middleage crisis is involved. The average PPL (at least the regular ones) tends to be in the slightly older range and there is a general view that any extra aviaton kit is a sign of showing off. Combine that with a bit of the Great British Sense of Modesty and I can see why the orginal poster is facing the problems he's facing.
People will go to all kinds of lengths to put you down and you'll get all kinds of ludicrous statistics. FACT: many more pilots have died as a result of not wearing a helmet than have died as a result of wearing one, never heard of the latter.
Since the field of aviation you intend to work in requires you to wear a helmet, i think you are perfectly right in your decision to wear one now and your insructor's attitude is quite appalling.
Good luck with your flying
Capt. M