Narrative:

During preflight imxt 4.0 was entered into FMC fix page to identify 4.0 DME around mdw to comply with turn requirements for the mbw 4 SID. Upon departure climb (runway 22L), started a 30 degree bank turn at 1300 ft MSL, right to 110 degree heading as instructed by the controller (tower). Upon radar contact with departure, the controller made a nonstandard phraseology statement that needed to be verified, 'come on -- get with the program.' after asking for clarification, he informed us he showed our aircraft position outside the 4.0 DME arc. Our navigation displays clearly showed us inside the 4.0 DME arc. After verifying this with the first officer's navigation display, I responded to the departure controller that we showed 3.7 DME on a heading of 110 degrees. His response was he didn't want to argue about it. After passing 10000 ft MSL, we verified our FMC alignment, IRU, and GPS position -- all checked good. Summary: departing runway 22L with an assigned heading of 110 degrees (right turn) on the mdw 4 SID starting your turn, at 1300 ft at 30 degree bank with a strong southwest wind (240 degrees at 45 KTS at 1000 ft AGL) this day will challenge the 4.0 DME requirement often. Accuracy of position is paramount, which system are to be controling, aircraft or ATC? Which NAVAID DME is to be used imxt/imdw? The SID offers both. An assigned heading further right may have been giving this controller the buffer he was looking for, and I appreciate his concern for us, and his airspace, but I cannot operate my aircraft in an unsafe manner to compensate for an inaccurate position. The SID should clearly depict which DME should be used to identify 4.0 DME.

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Original NASA ASRS Text

Title: AN ALLEGED TRACK VIOLATION MADE BY DEP CTLR WHEN HE CITES A B737 FOR TURNING OUTSIDE OF THE 4 NM RADIUS FROM MDW, IL.

Narrative: DURING PREFLT IMXT 4.0 WAS ENTERED INTO FMC FIX PAGE TO IDENT 4.0 DME AROUND MDW TO COMPLY WITH TURN REQUIREMENTS FOR THE MBW 4 SID. UPON DEP CLB (RWY 22L), STARTED A 30 DEG BANK TURN AT 1300 FT MSL, R TO 110 DEG HDG AS INSTRUCTED BY THE CTLR (TWR). UPON RADAR CONTACT WITH DEP, THE CTLR MADE A NONSTANDARD PHRASEOLOGY STATEMENT THAT NEEDED TO BE VERIFIED, 'COME ON -- GET WITH THE PROGRAM.' AFTER ASKING FOR CLARIFICATION, HE INFORMED US HE SHOWED OUR ACFT POS OUTSIDE THE 4.0 DME ARC. OUR NAV DISPLAYS CLRLY SHOWED US INSIDE THE 4.0 DME ARC. AFTER VERIFYING THIS WITH THE FO'S NAV DISPLAY, I RESPONDED TO THE DEP CTLR THAT WE SHOWED 3.7 DME ON A HDG OF 110 DEGS. HIS RESPONSE WAS HE DIDN'T WANT TO ARGUE ABOUT IT. AFTER PASSING 10000 FT MSL, WE VERIFIED OUR FMC ALIGNMENT, IRU, AND GPS POS -- ALL CHKED GOOD. SUMMARY: DEPARTING RWY 22L WITH AN ASSIGNED HDG OF 110 DEGS (R TURN) ON THE MDW 4 SID STARTING YOUR TURN, AT 1300 FT AT 30 DEG BANK WITH A STRONG SW WIND (240 DEGS AT 45 KTS AT 1000 FT AGL) THIS DAY WILL CHALLENGE THE 4.0 DME REQUIREMENT OFTEN. ACCURACY OF POS IS PARAMOUNT, WHICH SYS ARE TO BE CTLING, ACFT OR ATC? WHICH NAVAID DME IS TO BE USED IMXT/IMDW? THE SID OFFERS BOTH. AN ASSIGNED HDG FURTHER R MAY HAVE BEEN GIVING THIS CTLR THE BUFFER HE WAS LOOKING FOR, AND I APPRECIATE HIS CONCERN FOR US, AND HIS AIRSPACE, BUT I CANNOT OPERATE MY ACFT IN AN UNSAFE MANNER TO COMPENSATE FOR AN INACCURATE POS. THE SID SHOULD CLRLY DEPICT WHICH DME SHOULD BE USED TO IDENT 4.0 DME.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.