A non-GPS RNAV equipped aircraft departed on the atl SUMMT9 RNAV flying with VNAV engaged and indica...

Attributes
ACN	1292515
Time
Date	201508
Local Time Of Day	1201-1800
Place
Locale Reference	ATL.Airport
State Reference	GA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Initial Climb
Route In Use	SID SUMMT9 RNAV
Flight Plan	IFR
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 207 Flight Crew Total 6500 Flight Crew Type 530
Person 2
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Instructor Flight Crew Flight Engineer
Experience	Flight Crew Last 90 Days 195 Flight Crew Total 12000 Flight Crew Type 2639
Events
Anomaly	Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Narrative:

After a normal take off from runway 8R at katl; I instructed the captain who was pm to select 'navigation' mode at 400 feet AGL; as per our procedures. I verified navigation trk mode engaged. Shortly after; tower asked if we were direct to the first RNAV waypoint on the departure; 'ronii'. I had the RNAV progress page up which displays the aircrafts lateral deviation from the course. It showed .2 NM right; not uncommon. The captain indicated we were direct to the point. Tower then gave us heading to the northeast; and switched us to departure control. Just before initiating the turn; the lateral deviation moved to .3 NM right. Departure asked us if we were RNAV capable; and captain replied we were. We stayed on the heading for a couple minutes; and eventually we were cleared to a waypoint further down the departure. No mention was ever made of possible deviation or that we were off course. Honestly; from our standpoint; it appeared to be a normal departure. ATC is indicating we were off course. Perhaps the RNAV was in error.our aircraft do not have GPS; and use only IRU's and ground based navaids. Maybe GPS would enhance the capability of the RNAV and provide more precise information. Also; pilots should strive to maintain 0 cross track error.

Original NASA ASRS Text

Title: A non-GPS RNAV equipped aircraft departed on the ATL SUMMT9 RNAV flying with VNAV engaged and indicating a 0.2 NM lateral deviation. ATL asked if they were direct RONII; the FMS indicated they were but a vector was given.

Narrative: After a normal take off from Runway 8R at KATL; I instructed the Captain who was PM to select 'NAV' mode at 400 feet AGL; as per our procedures. I verified NAV TRK mode engaged. Shortly after; Tower asked if we were direct to the first RNAV waypoint on the departure; 'RONII'. I had the RNAV progress page up which displays the aircrafts lateral deviation from the course. It showed .2 NM right; not uncommon. The Captain indicated we were direct to the point. Tower then gave us heading to the northeast; and switched us to departure control. Just before initiating the turn; the lateral deviation moved to .3 NM right. Departure asked us if we were RNAV capable; and Captain replied we were. We stayed on the heading for a couple minutes; and eventually we were cleared to a waypoint further down the departure. No mention was ever made of possible deviation or that we were off course. Honestly; from our standpoint; it appeared to be a normal departure. ATC is indicating we were off course. Perhaps the RNAV was in error.Our aircraft do not have GPS; and use only IRU's and ground based NAVAIDs. Maybe GPS would enhance the capability of the RNAV and provide more precise information. Also; pilots should strive to maintain 0 cross track error.

Data retrieved from NASA's ASRS site 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.

A non-GPS RNAV equipped aircraft departed on the atl SUMMT9 RNAV flying with VNAV engaged and indicating a 0.2 NM lateral deviation. Atl asked if they were direct ronii; the FMS indicated they were but a vector was given.