Q:

What are Airport scan requests?

I have a lot of logging noise that seems to be malignant, and doesn't scream "problem" when I look at it. It is just so frequent that it's almost endless, and that it's related to wireless networking I'd like to know what it means (for various reasons like security or battery life...).
Being network related I disabled Bluetooth, and with the Thunderbolt Bridge changed the Configure IPv4 setting to Off. I think it's safe to say all of these messages happen while I'm connected to a trusted network.
What is the meaning of this information that the software engineers decided was worth logging?
System info
Hardware Overview:
  Model Name:   MacBook Pro
  Model Identifier: MacBookPro11,1
  Processor Name:   Intel Core i5
  Memory:   16 GB
  Boot ROM Version: MBP111.0138.B11
  SMC Version (system): 2.16f68
System Software Overview:

  System Version:   OS X 10.10 (14A389)
  Kernel Version:   Darwin 14.0.0
  Boot Volume:  Macintosh HD
  Boot Mode:    Normal
WiFi:
  Software Versions:
  CoreWLAN: 5.0 (500.35.2)
  CoreWLANKit:  4.0 (400.35)
  Menu Extra:   10.0 (1000.33.2)
  System Information:   9.0 (900.9)
  IO80211 Family:   7.0 (700.52)
  Diagnostics:  4.0 (400.68)
  AirPort Utility:  6.3.4 (634.17)
  Interfaces:
en0:
  Card Type:    AirPort Extreme  (0x14E4, 0x112)
  Firmware Version: Broadcom BCM43xx 1.0 (7.15.124.12.8)
  Locale:   FCC
  Country Code: US
  Supported PHY Modes:  802.11 a/b/g/n/ac

Log sample
10/24/14 1:01:45.000 AM kernel[0]: en0::IO80211Interface::postMessage bssid changed
10/24/14 1:01:45.000 AM kernel[0]: IO80211AWDLPeerManager::setAwdlOperatingMode Setting the AWDL operation mode from AUTO to SUSPENDED
10/24/14 1:01:45.000 AM kernel[0]: IO80211AWDLPeerManager::setAwdlSuspendedMode() Suspending AWDL, enterQuietMode(true)
10/24/14 1:01:45.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:01:45.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:01:45.000 AM kernel[0]: IO80211ScanManager::scanDone: Scheduling cache purge timer in 30 seconds.
10/24/14 1:01:45.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:01:45.000 AM kernel[0]: en0::IO80211Interface::postMessage bssid changed
10/24/14 1:01:46.000 AM kernel[0]: IO80211AWDLPeerManager::setAwdlOperatingMode Setting the AWDL operation mode from SUSPENDED to AUTO
10/24/14 1:01:46.000 AM kernel[0]: IO80211AWDLPeerManager::setAwdlAutoMode Resuming AWDL
10/24/14 1:01:52.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:01:52.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:11.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:12.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:12.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:12.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:12.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:12.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:12.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:13.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:13.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:13.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:13.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:13.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:13.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:14.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:14.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Scan request received from 'airportd' (pid 29) (2 SSIDs, 0 BSSIDs).
10/24/14 1:02:14.000 AM kernel[0]: IO80211ScanManager::startScanMultiple: Initiating scan.
10/24/14 1:02:14.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:14.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:02:14.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:16.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:02:16.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:17.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:02:17.000 AM kernel[0]: IO80211ScanManager::cachePurge: Rescheduling in 24 seconds.
10/24/14 1:02:22.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:02:22.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:02:41.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:02:41.000 AM kernel[0]: IO80211ScanManager::cachePurge: Rescheduling in 6 seconds.
10/24/14 1:02:47.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:02:47.000 AM kernel[0]: IO80211ScanManager::cachePurge: NOT Rescheduling.
10/24/14 1:03:51.000 AM kernel[0]: IO80211ScanManager::scanDone: Scheduling cache purge timer in 30 seconds.
10/24/14 1:03:57.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:03:57.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:04:21.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:04:21.000 AM kernel[0]: IO80211ScanManager::cachePurge: Rescheduling in 29 seconds.
10/24/14 1:04:25.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:04:25.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:04:50.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:04:50.000 AM kernel[0]: IO80211ScanManager::cachePurge: Rescheduling in 29 seconds.
10/24/14 1:04:54.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:04:54.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:05:19.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:05:19.000 AM kernel[0]: IO80211ScanManager::cachePurge: Rescheduling in 26 seconds.
10/24/14 1:05:20.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:05:20.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:05:45.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:05:45.000 AM kernel[0]: IO80211ScanManager::cachePurge: NOT Rescheduling.
10/24/14 1:08:38.000 AM kernel[0]: IO80211ScanManager::scanDone: Scheduling cache purge timer in 30 seconds.
10/24/14 1:08:43.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:08:43.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:09:08.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:09:08.000 AM kernel[0]: IO80211ScanManager::cachePurge: NOT Rescheduling.
10/24/14 1:10:45.000 AM kernel[0]: IO80211ScanManager::scanDone: Scheduling cache purge timer in 30 seconds.
10/24/14 1:10:50.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:10:50.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:15.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:11:15.000 AM kernel[0]: IO80211ScanManager::cachePurge: NOT Rescheduling.
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::scanDone: Scheduling cache purge timer in 30 seconds.
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:42.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:43.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:43.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:43.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:44.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:44.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:44.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:45.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:45.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:45.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:45.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:45.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:45.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:46.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:46.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:46.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:46.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:46.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:46.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:46.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:46.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:46.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:47.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:47.000 AM kernel[0]: IO80211ScanManager::startScan: pid 29 had pending scan request. Deleting.
10/24/14 1:11:47.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:47.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:47.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:48.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:48.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:48.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:49.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:49.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:49.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:49.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:49.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:49.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:49.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:49.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:49.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:50.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:50.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:50.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:51.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:51.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:51.000 AM kernel[0]: IO80211ScanManager::startScan: Initiating scan.
10/24/14 1:11:52.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:11:54.000 AM kernel[0]: IO80211ScanManager::startScan: Broadcast scan request received from 'airportd' (pid 29) ().
10/24/14 1:11:54.000 AM kernel[0]: IO80211ScanManager::getScanResult: All scan results returned for 'airportd' (pid 29).
10/24/14 1:12:12.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:12:12.000 AM kernel[0]: IO80211ScanManager::cachePurge: Rescheduling in 7 seconds.
10/24/14 1:12:19.000 AM kernel[0]: IO80211ScanManager::cachePurge: clearEntries[0] Firing!
10/24/14 1:12:19.000 AM kernel[0]: IO80211ScanManager::cachePurge: NOT Rescheduling.

A:

The scan requests are the system (the airportd dameon) scanning for available WiFi networks. In reviewing the log, it seems to do it in earnest for a minute, then slow down for several minutes, then pick back up. I'm not sure why it is doing it so often, but as long as your battery life does not seem to be suffering and the system is not slowing during these periods, I wouldn't worry about it.

