Weight Limited Flights

[TomH1408]

Im doing a study on fires aboard cargo aircraft, can anyone tell me roughly what percentage of cargo flights have the maximum allowable payload onboard. I dont need exact numbers just a ballpark figure.

Thanks for your help

[46mph]

All kinds of max weights; what do you mean: max ZFW/ TOW/ LW?

[TomH1408]

Its not the weight I need its the number of flight that leave with MAX PAYLOAD. I.e. 10% of cargo flights leave with the max payload posisble.

[Fish Head on Final]

If Carco flts leave with 10% load you dont last long.
it is more than payload.Its dangerus goods on bord:}.
That is the danger for fire

[TomH1408]

Thanks fish head, Im using this information to work out how much it would cost companies if their max payload on their aircraft was reduced because of the weight of a fire suppression system.

[Hunter58]

Fire suppression system?

Oxygen masks on, dive, depressurize, done!



In fact, most carriers will carry around 100% on one leg, and if they don;t you'll read about them in the economics section of the news (header: bankrupcies).

[G&T ice n slice]

Using data for sectors into/out of/with USA

Only 1.36% of flown sectors were operated at 99% or higher of declared available payload

In effect you have (1) fuel cost of incorporating a system into the aircraft. this cost exists permanently (2) income loss in case of reduce payload.

Unless a system is v.heavy MOST flown sectors are not payload limited, rather they are structurally limited in some way.

hummm

[TomH1408]

Cheers G&T thats exactly what I needed

[AerospaceAce]

TomH1408
Cargo carriers get paid by the Kg carried therefore they want max payload then fuel to the MTOW for the local condtions ie temp, runway length, and airport alt. Most operators opt payload before fuel and the stop enroute for more fuel rather than a direct flight and less payload.
They want an a/c with min basic weight and will not go for a system that increases the a/c weight unless it is made mandatory.

[Ingwe]

Nice idea but possibly a bit academic. That system going to be extra weight, means extra fuel, means less profit so unless it's in the regs no airline is going to fit it.

[Intruder]

Its not the weight I need its the number of flight that leave with MAX PAYLOAD. I.e. 10% of cargo flights leave with the max payload posisble.
That would be close to 0%.

Almost all flights balance payload and fuel for range and landing fuel considerations. I cannot think of even 1 time in 10 years that one of our 747Fs has been loaded to max payload (i.e., max ZFW).

OTOH, we often (10-15%?) fly at max TOGW, which means max payload for the planned sector.

[Deltabravowhiskey]

To keep it simple for the guy differentiate ACMI from Scheduled.

ACMI can fly empty and turn a profit since the customer pays for the aircraft regardless of load and who also determines how much is loaded within the limits of the aircraft. Often aircraft are selected by max available payload or volume or specific dimensional requirements (i.e. Nose loaders whose ability to carry very long items on the main deck can be the sole criteria of aircraft selection).

Scheduled (HKG, SHA etc) are always at or near max volume/weight hence the stop in ANC. These flights are filled by freight generated by the service provider or a combination of multiple freight forwarders who buy positions in advance. If one does not fill a position another is waiting to take their place to insure the flight departs with maximum revenue onboard.

Fire suppression, hot topic for sure.

The first line of defense is smoke detection, if you can dump the cabin (raise it to 25,000 feet) and suppress a hot spot thru removal of air and injection of Halon before it turns into a full blown fire your odds of surviving are greatly increased if not assured.

In the case of UPS in PHL, they could not get to the source of the smoke and this resulted in a uncontrollable fire, if they were over water it would have been an ocean ditching for sure. Lucky for them it was over land, and they put it down just in time (flames already compromised the structure while still airborne).

If you are overwater and have smoke, don oxygen depressurize to 25,000'+ cabin altitude, combat smoke by injecting halon, speed: M.92 (plus a few for momma and the kids) to the nearest "dry spot" and LAND... if you have a fire and you're unable to contain or suppress it, you're gonna get wet. In this case no fire suppression system is gonna help you since the fire is obviously out of control and being fed by an oxidizer or lithium batteries (assuming the cabin was dumped to 25,000 feet or more at this point).

Fire suppression is great for a warehouse when weight is not a factor and you have an unlimited suppression source (water). The fact remains that (and luckily so) fires are extremely rare. Unfortunately fire suppression systems are extremely heavy in respect to a size that is able to combat the volume of a freighter. Even then you have a limited amount of suppression capability due to size/weight constraints.

The fact remains that the most effective means to combat a fire is to take the suppression system to the fire rather than a massive flood of suppression throughout the cabin. Sadly, suppression systems don't provide fire suppression capability to the most likely causes (oxidzers, Lithium batteries or other types of thermal runaway).

DB

[GlueBall]

There just aren't enough inflight cargo fires to convince the regulatory authorities to mandate new fangled on board fire surpression installations; much less to convince airlines to voluntarily spend billions of dollars for it.

Lower hold baggage compartments already have fire detection and suppression systems. On cargo-only airplanes the emphasis is on proper dangerous goods packaging and handling to preclude fires, rather than uplifting a fire department to fight fires.

A much larger concern is explosives. Resources must be spent on explosives detection equipment to scan baggage and cargo. :ooh:

[TomH1408]

Thank you all for your posts.

Just to let you know I needed the information as part of a study to look at the costs of installing the systems (installation, maintenance, extra fuel, loss of income due to added weight hence the original post, etc) against the benefit i.e. money saved by avoiding accidents caused by onbaord cargo fires.

Thanks again

Tom

[CR2]

Many experienced contributors have mentioned that they are very rare. The only two that spring to mind are the SAA "Helderberg" 74M 20ish years ago and the Valujet DC9 (pax a/c, today's Airtran (must be at least 15... too lazy to check)).

I've been in the game for 20 years. Hunter58 has it about right I'd say...

[offa]

..... and BOTH were carrying things they shouldn't have been carrying in the first place so a fire suppression system wouldn't have been helpful or necessary in either case?:(

[Whaledog]

D,B,W, Good post,
My Flight s to the USA are always heavey. At max wt for that segment on a B747. IF not payload , pilot added fuel. If light I always try and find room for that extra fuel. Min release with bad wx in anc....Everyone know that if anc goes down hard the wx 5 miles to the North east is always VFR, It must be true my " flight following " dispatch says so... :ugh:
Now the flight from anc to the lower 48 require less fuel= lighter wt on those leg.
Now USA back to ASIA /Africa/Sa. I worry more about the D.G. on board. Nasty stuff. Kicked a pallet off my plane this month in the middle of loading.
I;m more worried about shippers and contract loaders than the fire system.
No fire surpression system we can carry can meet the fire fighting requirments of the D.G item we carry....Much more importat to watch / inspect the D.G. loads.

17 more years to retirement. ( I hope)