In an emergency situation, an aircraft must be evacuated in under 90 seconds, even with half of the exit doors non-functional. Time is undoubtedly critical, and recent events have shown that this is seldom achieved. Manufacturers are required to demonstrate that their aircraft can be evacuated within this timeframe through testing, although it could be argued that this regulation should be reassessed and tested under more realistic conditions. Additionally, passengers need to be educated on the fact that taking baggage with them can hinder the evacuation process, thereby endangering the lives of fellow passengers and the crew, who are the last to exit after ensuring no one is left onboard.
Baggage can also cause damage to the evacuation slide. Regardless of whether it is a Boeing or Airbus aircraft, the operation of the doors and the evacuation slide is vital for safety, emphasizing the need for a swift evacuation without relying on airstairs or ground equipment. However, crew members will attest that there is a significant difference in the operation of doors between Boeing and Airbus aircraft.
How a Slide Is Deployed
During an evacuation, flight attendants are responsible for deploying emergency slides, which are connected to either the door or the door frame, depending on the aircraft type. Both Boeing and Airbus main cabin exits feature plug-type doors, but they function quite differently. These doors cannot be opened while the aircraft is pressurized. Depending on the specific aircraft model, there may also be overwing exits that operate differently. The slides are stored in containers attached to the main cabin doors and can be either armed or disarmed. When disarmed, the door can be opened safely.
As reported by Smithsonian Magazine, when the door is opened from the inside while armed, a lanyard activates the slide deployment mechanism. A cylinder containing carbon dioxide under pressure inflates the slide. The pressurized gas travels through flexible hoses to an aspirator, which has small doors that open due to the vacuum created by the high-speed air from the cylinder. This process draws in ambient air from outside, further aiding in the slide’s inflation.
The pressure within the cylinder can be monitored via an indicator on the slide storage. Slide deployment occurs automatically when the door is armed, but if inflation fails, a manual inflation handle is located on the right side of the slide. The slide typically takes between six and ten seconds to fully inflate.
Operating a Boeing Door on the 737
On many Boeing models, particularly the 737, arming the door is a more hands-on and physical task compared to its Airbus counterpart. The distinction lies in how each manufacturer connects the escape slide to the aircraft. For Boeing, arming the door requires the flight attendant to manually move the girt bar, a metal bar located at the bottom of the folded slide. This bar is lifted by hand and detached from its stowed brackets on the door, then latched into a fitting on the cabin floor.
This process ensures that when the door is opened, the slide is pulled out and inflates. The next step involves placing a red warning streamer across the window to indicate that it is armed, making it visible from both inside and outside the aircraft. This manual action is coupled with an arming lever that swings across the door, which can be cumbersome and heavy for the crew to operate. Disarming the door involves reversing this process, moving the girt bar back onto the door from the floor. The girt bar prevents the slide from deploying and inflating.
Boeing doors function by being pulled slightly inward before swinging outward horizontally, aligning the exterior of the door with the fuselage. The interior of the door is visible when standing outside the aircraft. Airstairs should always be in place before a crew member opens or closes a door, and the safety strap must be engaged when the door is open.
The Airbus Difference
Airbus has simplified the door operation process significantly compared to Boeing.
Source: Original article
