"MacBook Air EFI Firmware Update 2.9.1 (4.3MB)
This update replaces EFI Firmware Update 2.9 and is recommended for MacBook Air (Mid 2011) models. This update addresses an issue where systems may take longer to wake from sleep than expected and fixes a rare issue that may cause fans to run at full speed after waking from sleep.

After the update, the EFI (Boot) ROM will be MBA41.0077.B11

System Requirements:
OS X 10.9.2 and later"

(The original D/L page had MBA41.0077.B11 under 'Requirements", a typo as that was the EFI version after installing the (pulled) v2.9 update. (Same version installed by 2.9.1 also.) The previous/pulled EFI 2.9 update requirements noted having EFI 0077.B00, .B08, .B0E or .B0F.)
Check MacBook Air forum for feedback on v2.9.1. (Early report from 13" 2011 MacBook Air owner said he updated OK. Boot rom MBA41.0077.B11 after EFI 2.9.1 update.)
 

• Mac OS X versions (builds) for computers (added Mid-2014 MacBook Pros & iMac)
• MacBook Pro (Retina, Late 2013 (and later): Using 192 kHz sample rate digital audio
• Mac computers: How do I configure PPPoE on a new computer?
• Recovering a lost firmware password (MacBook Air (Late 2010 and later), MacBook Pro (Early 2011 and later), iMac (Mid 2011 and later), Mac mini (Mid 2011), Mac Pro (Late 2013):
  
  
• Using 4K displays and Ultra HD TVs with Mac computers
• MacBook Pro: Frequently asked questions about using a Retina display
• Avoiding image persistence on Apple displays
• About integrated video on Intel-based Macs
  
  
• Using USB 3 devices on Mac computers FAQ
• Thunderbolt ports and displays: Frequently asked questions (FAQ)
• Mac computers: Apple USB SuperDrive and MacBook Air SuperDrive compatibility
• Intel-Based Apple notebooks: Identifying the right power adapter and power cord