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The purpose of FLAPS-2-APPROACH is two-fold:  To document the construction of a Boeing 737 flight simulator, and to act as a platform to share aviation-related articles pertaining to the Boeing 737; thereby, providing a source of inspiration and reference to like-minded individuals.

I am not a professional journalist.  Writing for a cross section of readers from differing cultures and languages with varying degrees of technical ability, can at times be challenging. I hope there are not too many spelling and grammatical mistakes.


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I use the words 'modules & panels' and 'CDU & FMC' interchangeably.  The definition of the acronym 'OEM' is Original Equipment Manufacturer (aka real aicraft part).


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Journal Archive (Newest First)

Entries in Aural Warnings (2)


RAAS Professional By FS2Crew - Review

Runway incursions are a leading cause of aviation fatalities and account for approximately $1 billion annually in aircraft damages. To help prevent such losses, close calls and collisions, the industry requested a safety system that would help maintain situational awareness during taxiing and preparing for takeoff and landing. 

Honeywell stepped in to fill the gap by developing an easy-to-install heads-up advisory system with aural alerts (call-outs) to increase flight crew situational awareness during ground and air operations relative to the runway. 

This system was then further improved upon, with the collaboration of Emirates.

LEFT:  KLAX airport diagram showing the maze that hundreds of aircraft each day must safely navigate.  Given the complexity of many airports, it's amazing there are not more runway incursions (click to enlarge).

I previously used a shareware version of RAAS developed by PlaneMan in South Korea.  This small FS add-on worked well, however, recently it stopped working on my system for an unknown reason.  I wrote a review on FsRAAS by Planeman in 2011.  Searching for a replacement, I came across RAAS Professional developed by FS2 Crew.  

What is RAAS

RAAS is an acronym for Runways Awareness And Advisory System (RAAS).  RAAS was developed by Honeywell Aerospace as a simple to install but effective software addition to the Honeywell Enhanced Ground Proximity Warning System (EGPWS).  Although the base-line RAAS is still in operation, Honeywell has improved the software by integrating additional aural advisory call-outs; in particular, relating to stabilised approaches.  SmartRunway and SmartLanding are the next generation of RAAS.

RAAS Professional replicates the complete aural Honeywell suite (RAAS, SmartRunway and SmartLanding), however, does not simulate the visual advisory displays.


Installation is via an installer and is straightforward.  The software installs a .ddl file which is loaded automatically when you begin a new simulation flight.  Once installed, a tab (RAAS Professional) will be added to the menu bar in flight simulator; this is where the user interface is opened to configure the program.  I did not experience any issues installing this program.

RAAS uses Simconnect to connect to flight simulator and does not require the use of FSUPIC.

Be aware that problems can occur when attempting to connect any add-on software that uses Simconnect (as opposed to FSUPIC).  If a problem occurs, the easiest way to rectify it is to re-install the Simconnect module of flight Simulator.

Simulator Platforms

RAAS will operate on FS9, FSX and P3D V3 simulation platforms in 32 Bit.  A 64 Bit version of the program caters towards those using P3D V4.

Initial Configuration (Managing the Runway Database)

The most important task to complete prior to configuring RAAS is to download a small standalone program called MakeRunways.  This software has been developed by Peter Dowson and is available gratis from his website.  The MakeRunways utility should be placed in your main flight simulator folder where the Scenery.cfg file is located.    

When run, MakeRunways interrogates the scenery folder and generates several database files that include, amongst other things, the runways found in flight simulator.  The generated files are automatically saved to your main flight simulator folder, for programs such as RAAS, to access and read. 

Whenever you install new scenery you must run the MakeRunways utility to ensure that the database is synchronized and up-to-date, otherwise RAAS will not work with the new add-on airport scenery.

Of importance, is that the 64 Bit version of RAAS requires an additional program to be installed.  The reason for this, is that vP3D V4 use a dedicated addons folder.  The Add-on organizer enables the add-on folder in P3D V4 to be interrogated by the MakeRunways program. 

The Lorby Prepar 3D Addon Organizer can be downloaded gratis at the developers website (see downloads section). 

The installation of these programs is very straightforward and instructions are provided in the supporting documentation.

Advanced Configuration

RAAS, like its real world counterpart, is highly configurable from the User Interface (UI) accessed from the Add-Ons menu bar in flight simulator.

The following aural call-outs (advisory) are available.

Approaching Runway (On Ground): advisory provides the flight crew with an awareness of when a runway is being approached.
Approaching Runway (In Air): advisory provides the flight crew with an awareness of which runway the aircraft is lined-up with during approach.
On Runway: advisory provides the flight crew with an awareness of which runway the aircraft is lined up with on the ground.
Runway End: advisory is used to improve crew awareness of the runway end during low visibility operations.
Taxiway Take-off: advisory alerts pilots to excessive taxi speeds or an inadvertent takeoff on a taxiway.
Insufficient Runway Length (On Ground): provides the crew of an awareness of which runway the aircraft is lined-up with and if the runway length available is less than the defined minimum takeoff length.
Extended Holding on Runway: alerts the crew of an extended holding period on the runway.
Approaching Short Runway (In Air): offers an advisory of which runway the aircraft is lined-up with and if the runway length available is sufficient as defined in the Runways section.
Taxiway Landing: alerts the crew if they are not lined up with a runway at low altitudes.
Takeoff Flap Monitor: alerts the crew if the aircraft's flaps are not in the defined takeoff range.
Landing Distance Remaining: provides the flight crew with an awareness of the runway length remaining during roll-out.
Distance Remaining (Rejected Takeoff): provides the flight crew with an awareness of the runway length remaining during a rejected takeoff.
Landing Flap Monitor: advisory alerts the crew if the landing flaps are not set.
Excessive Approach Speed: is an alert if the aircraft speed become excessive compared to the final approach speed.
Excessive Approach Angle: is an alert if the aircraft's approach angle becomes too steep.
Altimeter Setting (Above Transition): alerts the crew if the altimeter is not set to standard after climbing above the transition altitude.
Altimeter Setting (Below Transition): provides the flight crew with an awareness of improper corrected altitude setting while below the transition altitude.
Long Landing: alerts the flight crew if the aircraft has not touched down within the pre-defined Touchdown Zone Length.
Caution Enabled: adds the phrase ‘Caution’ to select aural calls.

Any of the aural call-outs can be turned on or off and several parameters are configurable from the UI.  Additionally, specific parameters can be changed depending upon aircraft type or airline policy, such as:

•    Aircraft type.
•    Runway takeoff and landing length, runway length and touchdown zone.
•    Hold times (initial hold time and repeats).
•    Flaps configuration (takeoff, landing, upper and lower altitudes).
•    Approach speeds.
•    Transition altitudes.
•    Extended hold times and frequency of the aural call-out.

If you fly different aircraft, any number of user profiles can be created.  The profiles are associated with the aircraft type selected in flight simulator.

Comparison - RAAS Professional to the  Honeywell System

RAAS Professional by Fs2Crew replicates the real Honeywell system surprisingly well.  The aural call-outs are identical and the female voice sounds very similar to the voice used by Honeywell - which provide either a female or male voice.  If you’re keen to compare RAAS to the Honeywell system I recommend you visit the Honeywell website and watch the three (3) videos at the bottom of the web page.

LEFT:  RAAS Professional User Interface (UI).  Click to enlarge.

Turning RAAS On and Off (RAAS Master Switch)

RAAS can be turned on and off ‘on the fly’ from the User Interface (UI), or by assigned a hot-key (key event API) in flight simulator.  By default the on/off function has been assigned to the water rudder (R) function (from within the flight simulator control panel).  It is also possible to assign this functionality to a switch/toggle.

Sound Cards and System Test

RAAS has been designed to be used within multiple speaker environments, and changing the speaker preference is made directly in the User Interface (UI).  With a little tinkering you should be able to dedicate the RAAS aural call-outs to a separate speaker while maintaining engine noise and Air Traffic Control to other speakers and a headset.  A master volume control tab enables the sound levels to be adjusted (if the speaker does not have volume control knob).

The UI has a System Test to determine correct configuration and connection (audio test) and an error log.  The error log can be used during troubleshooting (if necessary).  

Voice Sets and Memory Use

Currently RAAS only supports English in a female voice.  I believe that additional foreign language voice sets may be released in due course.

When RAAS is running, there is no discernable effect on the computer or flight simulator.


A detailed and easy to read manual is supplied with the program.  The manual, in addition to providing detailed installation instructions, also has a very good troubleshooting section in the unlikely event that you have problems during the installation process.

RAAS supports a dedicated support forum and the developer replies to questions when asked.  

Program Shortfalls

At the moment it is not possible to install RAAS on a client computer and run the program across a network.  Although RAAS does not use a lot of computer resources, some users may wish to display the UI (when required) on a client screen in association with the Instructor Station.

Another shortfall is the inconsistent operation of the key event API (that enables you to connect a switch/toggle to the on/off function / RAAS Master Switch).  Sometimes it works and at other times it does not work correctly.

Final Call

If you seek realism, RAAS is a worthwhile addition to flight simulator.   When configured to an appropriate aircraft, the aural call-outs are timely and helpful to situational awareness.  Two features I particularly like are the ability of RAAS to remind you to set the appropriate flaps detente prior to takeoff, and the aural call-out that is generated which identifies the runway you are aligned with during final approach.

I must admit there was one occurrence when I was conducting a VOR approach to a parallel runway in limited visibility.  The aural call-out stated I was aligned to runway 24 Left when I was supposed to landing on runway 24 Right!  But isn’t this the reason RAAS was designed – to stop incursions and provide situation awareness to flight crews.

References and Affiliation

This article was written with reference material obtained from Honeywell Aerospace.  

Please note I have no affiliation with FS2Crew.  I have not been provided with ‘free’ software, nor did I receive a discount in return for a favourable review.  The comments and recommendations I have made are my own.  Further information on RAAS Professional can be obtained directly from the FS2Crew website.

Flight Simulator, in this article, refers to FSX/FS10.  I use the B737 avionics suite developed by ProSim-AR.

Another article relating to a free version of RAAS can be read here -  Runway Awareness and Advisory - FS Add-On.

BELOW:  Honeywell promotional video (courtesy & with permission Honeywell).

BELOW:  RAAS Professional promotional video (courtesy FS2Crew).


B737 Aural Warning Module (AWM) Installed and Operational

One of the recent upgrades to the simulator has been the installation of an Aural Warning Module (AWM).  This module resides on the first officer side of the flight deck and is attached to the forward bulkhead of the Main Instrument Panel directly beside the throttle quadrant.  The module replaces four of the computer-synthesised warnings with the OEM counterparts.

LEFT:  Front of the AWM.

The purpose of the module is straightforward; to provide a fail-safe mechanical device that delivers loud, clear and concise tones and bells to indicate to the flight crew that major problem or configuration issue exists.  The aural alarms activate in unison with warning lights that are located on the forward overhead panel, fire suppression panel and on the glare shield of the Main Instrument Panel (six pack annunciators and master fire warning (bell cutout) and master caution buttons).

What's in the Grey Box

The aural warning box contains three mechanical devices capable of delivering four aural warnings: fire bell, clacker and a horn which activates either in a continuous or intermittent tone.    

The fire bell rings when any number of events relating to a fire on the aircraft occurs.  The fire bell can be silenced by either pushing the master fire warning button located on the glare shield or bellcutout switch located on the fire suppression panel.  I will be discussing at length the fire suppression panel in a future post; therefore, will not discuss the various scenarios that the fire bell operates.

The overspeeed clacker sounds when the aircraft exceeds the maximum allowable airspeed (Vmo /Mno).  The warning clacker can only be silenced by reducing your airspeed below Vmo / Mno.

The intermittent horn is an aural cue for the takeoff configuration alert.  The horn will sound when a configuration problem exists with the aircraft.  For example, advancing the throttles with the parking break set or the flaps not set.  

When the horn is activated a takeoff config warning light (in red) illuminates on the left forward overhead panel.  Deactivation of the alarm is by retarding the throttle levers to idle and then configuring the aircraft correctly.

The continuous horn is activated when specific flight conditions are met. The following are the main scenarios that activate this alarm.

  • The aircraft is below 800 feet radio altitude with flaps set from UP to flaps 10 with either throttle thrust lever set between idle and 20 degrees forward of idle.
  • The aircraft descends below 200 feet radio altitude (any configuration)
  • The aircraft has flaps set 15 through 25 with either throttle thrust lever set between idle and 20 degrees forward of idle.
  • Flaps 15 is selected without the landing gear being in the down position.
  • The aircraft has flaps set greater than flaps 25.
  • The aircraft’s landing gear is not extended.

Silencing the Continuous Tone Horn

The horn can be silenced by depressing the horn cutout switch located on the throttle quadrant; however, if the aircraft descends below 200 feet radio altitude, or the flaps are extended greater than Flaps 15 (without landing gear extended), the horn cutout switch will not silence the horn.  

Lowering the landing gear or ascending to higher altitude will silence and reset the horn.

OEM part (Original Equipment Manufacturer)

The grey box is not an OEM part; however, is similar to the module used in the 800 series with the exception of a toggle switch located on the upper part of the unit (the toggle switch is used by maintenance).  The box was replicated (using vacuform technology) to the identical measurements of the OEM counterpart.  The replica box will be replaced when and if I find a 800 series OEM part.

LEFT:  Inside the AWM from left to right: horn, clacker and bell.  The small box houses basic circuitry. 

The mechanical tones and bell have been acquired from a Boeing 737-200 series aircraft and retrofitted into the module.  I believe the only difference in tones is that the 800 series has additional tones and alarms fitted to the container (such as the auto pilot disconnect).


The aural tones are mechanical and not software generated.  To interface the warnings with ProSim737 a Phidget 0/0/4 card has been used.  This card is located within the Interface Master Module (IMM) and is connected to the aural warning module by a custom wired VGA cable.  The relays on the card are triggered when a specific condition, based on the offsets set within the avionics software, are met.

Authenticity and Volume

Although FSX, ProSim737, Sim Avionics and many other avionics suites include aural warnings within their package, the clarity and volume in sound produced by a mechanical device surpasses that of a computer generated sound.  

"A word of warning".  The horns and bell are loud – very loud… They are loud for a reason – to annoy a flight crew so that will not ignore the "urgency" of the alarm.  The first time the fire bell sounded during testing made me jump out of my skin!  It also activated the “yell” button on my girlfriend…  

The devices do not have a volume control.  To quieten the aural warnings for “inside” simulation use, I’ve installed foam around the mechanical devices and bell.  This has been successful in lowering the volume by around 60%. 

Below is a short video showing the Aural Warning Module and its various sounds (turn volume up).