Here's a report from Dr SIMON BROWN, Captain, Monarch Airlines, AvMed Dr.
Monarch invests in new demand flow oxygen system
Monarch's onboard oxygen systems are similar to those carried by most other airlines, the familiar therapeutic oxygen bottles which provide a constant flow at either 2 or 4 l/min.
They are always carried on board every aircraft because they are also designed for use as the "walk- around" sets required by the cabin crew in the case of a cabin decompression.
These will last for about 35 minutes on HI flow (4 l/min) and 70 minutes on LO flow (2 l/min).
Providing these to passengers who require a fairly constant oxygen supply presents logistical problems because of the number of additional oxygen bottles needed. To overcome this, Monarch invested in a new demand flow system known as "Zero-2", supplied by the Aeromedic Group (www.aeromedicgroup.com/what-we-do/zero-two)
Zero-2
This system has the advantage of working on a demand system where the oxygen is normally delivered via nasal cannulae. Some sets can deliver flow rates from between 0.5 to 6 l/min, but later models only deliver at the familiar rates of 2 or 4 l/min. At 4 l/min Zero-2 will last for about 15 hours and at 2 l/min it will last for 30 hours, so the advantages are obvious.
Zero-2 is also easily portable, designed to fit below the seat in front of the passenger for take off and landing (yet the cannulae will still reach the patient), but compact enough in its padded carry case to stand up next to the passenger's seat for monitoring or altering the dosage whenever the seat belt signs are off.
It can also supply oxygen at a constant flow, if required, or if the batteries fail or run out. It only needs two AA batteries to power it and spares are included in the set. Even without batteries, a flow rate of 2 l/min is available and the oxygen supply will still last for about 8.5 hours under these conditions.
The system is compatible with both adult and child therapeutic oxygen masks if required.
In case of decompression
The Zero-2 system cannot provide sufficient oxygen following a decompression. In this case a normal dropdown mask must be worn, but this can be fitted over the Zero-2's nasal cannulae. Hence the passenger will get the dropdown oxygen at its constant flow rate as well as the Zero-2's therapeutic oxygen.
All of Monarch's cabin crews are trained in the operation of the Zero-2 sets, but it is not their responsibility to advise on the delivery rate that any individual passenger may need. This is the sole responsibility of the prescribing physician or the accompanying flight nurse.
In summary, Monarch has not changed its standard therapeutic oxygen sets and these are always carried on board. We can now, however, provide a better standard of supplementary oxygen for passengers who require it, but this must always be requested from the company in advance of the flight.